In a universe of apps there are plenty of crap and few big fishes (and really small caviar). As I have done before with other graphic design tools, I have hand picked the best of the crop.
This is time, the opportunity is for web apps. I used not to be a big fan of them but now days you can find a plethora of great fast loading well design right to the purpose apps. Apps like Aviary  and Pickmoney (luv this one) stands from the crowd, the first  for its near desktop quality tools in a free web app and the second for its great interface and down to the point and fast results.
I have rounded up the best Free Design Apps in a single post, hope you find some pearls and please tell me if I have forgot something to include it later.
Check more apps at:

• 45 Best Freeware Design Programs
• 40 Best Open Source Graphic Programs

DeviantartMuro

Deviantart Muro is a free, HTML5-powered drawing application. It includes 21 brushes, each uniquely programmed. Muro supports all HTML5-enabled browsers including the iPad. Muro allows users to create complete works of art, submit them directly to their Deviantart galleries, and join fellow deviants in a public forum to share drawings. The standalone tool is available in both Basic and Pro modes–Basic for beginning artists and Pro for more experienced users. Visit Site

iMapBuilder Online

iMapBuilder Online creates interactive flash map online, with clickable regions, points, and icons. Easily embed interactive online maps to any web site by simply copy and paste few lines of HTML code. Import your own custom images for converting into interactive image maps, For example, photos, floor plan, illustrations, pictures, blueprints, mockup images, airline routes, etc. Interactive map is created instantly online, with a permanent link which you can email to others for sharing, presentation, remote teaching, learning and more. Powerful interactive image mapping tool suitable for individuals, web design houses, Fortune 500 companies, schools, universities, associations, tourism companies, financial institutions and government departments use. Visit Site

Sweeble

Unique, browser-based software that handles everything involved in publishing news and information. From creating articles, to editing images, to designing your publication, to converting and outputting for CMYK printing. Do everything online in sweeble – from spellchecking to ordering print services. No need to buy or download any software. Built-in ad system so you can sell your own adverts and earn money through your publications. Dual publishing – you get a free website too. Simple, drag-and-drop user interface working with range of designs and page templates. Visit Site

A Web Whiteboard

A Web Whiteboard is touch-friendly whiteboard app that lets you use your computer, tablet or smartphone to easily draw sketches, collaborate with others and share them with the world. Visit Site

Fatpaint

With Fatpaint, anyone can create pages, images and illustrations, and have it printed on custom products such as iPhone cases, t-shirts, sneakers and promotional products. It is integrated with Zazzle, a world leading custom printed products company, so that at the press of a button, the design created by the user is accurately displayed on products from within the graphics editor. The user can then share these images on Facebook, buy or sell the product. Visit Site

Twiddla

Twiddla is a real-time online collaboration tool. Its beauty is in its simplicity and accessibility: no plug-ins or downloads, no need to work around complex firewalls, no advanced scheduling. It’s available 24-7 and the only requirement is a computer with an internet connection and a web browser. It’s browser-agnostic, user friendly, and probably more fun than you’re supposed to be having at work. Visit Site

Plan Layout Tool

A quick way to design a floor plan for your house. Select rooms and insert them into your plan. Move them around and re-size them until your plan is exactly the way you want it. The plan will automatically update the total square footage of your plan based on the rooms you added. You can design a single story plan or a two story plan. For a 2 story plan, you can overlay the other floor on your plan to see if the rooms line up. Visit Site

Aviary Raven

• Use Raven to create fully scalable vector art appropriate for logos or tee shirt designs. You won’t find a similar tool on the web.
• Powerful path engine – Work with paths, lines, curves, and objects. Control stroke, fill color, and gradient.
• Powerful layers – Work with layers, groups, and layer masks. Import scalable vector graphics (SVG) files.
• Share and learn – Collaborate with other users. Follow step-by-step tutorials to learn new skills.
• Import from popular photo-sharing sites – Import images from Flickr, Picasa, and Facebook.
• Complementary suite of creation tools – Use your Raven creations in other Aviary tools.

 

FlockDraw

When you start development on a project, all you have are a few ideas and a long road ahead. As time progresses, you get to watch the concept become reality. Little steps contribute to the bigger picture. Through the course of development, you hit roadblocks and stumble. Unseen problems become evident. You must adapt.But you don’t give up. You innovate. You conquer. You continue forward and exceed your own expectations. We’ve put a lot of love into this, and we’re proud to release it to the world. We hope you enjoy it. This one’s for you. Visit Site

Photo Editors

PicMonkey

If you loved Picnik, PicMonkey is back in town and better than ever. It’s faster, more powerful, and easier to use. It’s the real deal you already know, plus 78% more monkey. Visit Site

Picfull

Choose a picture…Apply a filter to it…Save and share it! Choose any photo you like to start editing. Choose from many custom photo effects. Save the photo to your computer or share it with your friends! Visit Site

Adobe Photoshop Express

Adobe Photoshop Express is an online version of the popular digital image-editing software. Crop, rotate, tweak, twirl and show off your photos. Sign up for a free account to upload and save up to 2GB of digital images for free. Display your photos to friends and family in various galleries such as grids or with 3D navigation. Visite Site

FotoFlexer

FotoFlexer is a powerful online digital photo editor in existence. Use FotoFlexer to perform effects previously available only to professionals using expensive software. Remove blemishes, change skin and hair color, morph photos, change backgrounds. Visit Site

LunaPic

LunaPic lets you pimp your profile pics for MySpace and FaceBook. Features include, Create a pixelated animation of your image instantly. See over 20 animation examples in our updated animation help page. Open images directly from your FaceBook Account. More animated effects added, including Groovy Rainbow. Create a Collage or Blend your images together. Reduce or Enlarge things in your photos with the new Cosmetic Surgery tool. We’ve also added cool sample images to use before you upload your own images. Use our completely free photo editor in your browser. Visit Site

Pixlr 0-matic

Visit Site

Pixlr Express

Visit Site

Pixlr Editor

Pixlr is the creator of online cloud-based image tools and utilities. Today we have three applications in our suite: Pixlr Editor, Pixlr Express and Pixlr-o-matic. They are built in Flash and you need to have the Flash plug-in (get flash) to get it to work, however, 98% of all computers have flash so you are probably set. We also provide screengrabbing tools Pixlr Grabber and one click photo sharing imm.io. Pixlr is now part of Autodesk, a global leader in innovative design software and services.
Visit Site

SumoPaint

Sumo Paint is a full featured photo editing / painting application, which works right in your favorite web browser! The application can be used in Windows, Macintosh or Linux operating systems. The only requirement is the Flash Player (which usually comes preinstalled in any OS). Visit Site

Image Publishing and Sharing

Bookr

Bookr is a tool to create and share your own photobook using Flickr images. Feel free to browse or create books, and send to your friends. Bookr, is one of pimpampum flickr toys. http://www.pimpampum.net/bookr/

Floor Planning

ExhibitCore Floor Planner

With a free account you have access to our extensive and growing inventory and tools to help you layout your event space planning or kitchen remodel and more. You will also be able to save all of your layouts for later use and even share your layout on facebook and other social media websites.In addition to floor plan capabilities, ExhibitCore Floor Planner is an easy cost-effective way to handle all of your event management needs. Visit Site

Fun

PuriCute

At PuriCute.com all your photo snappin dreams and fantasies come to life. Embellish your already cute self with our high quality and professionally designed graphics. Customize your photos in a matter of seconds by adding some twinkle twinkle to your googly eyes or stamping a strawberry tattoo on your best friends forehead. Resize the image by zooming in on the couple-shot with your latest flame and soften up the lighting to reveal that flawless complexion. Visit Site

Cubescape

A simple app that gives you some easy-to-use tools to create 3D pixel art on a large canvas. You can drop blocks down one at a time, on top of one another, and even explode them. The app tracks your progress and lets you or others play it back to see what you did, much like some of the fantastic tutorials that come with PhotoShop to show you how people create their digital masterpieces. Visit Site

Ultimate Flash Face

Have you ever wanted to be a police sketch artist? Or just wondered how they use the computer to generate their sketches? Well, now you can do both with Ultimate Flash Face. It provides a palette of facial objects: eyes, jaw, hair, etc. For each, you pick the one you like, then place and size it appropriately. Once you’ve finished creating your face, you can go to the options on the right side of the page and chose to save, delete or print your creation. Visit Site

Pixton

Pixton is an online user-generated comic strip. Without having to draw, people of all ages can share their ideas, opinions, and stories publishing them instantly to a worldwide web audience. An intuitive, contextual interface lets you build an episode quickly and easily, one scene at a time. Pixton characters are created by choosing from preset attributes and expressions, specifying hair and skin color, rotating body parts, and setting height and girth with a drag of the mouse. You have the option of allowing others to remix an episode. Pixton creates a duplicate episode which can then be altered or added to, without affecting the original. Any remixes are listed below an original episode, allowing viewers to follow its evolution. Visit Site 

Fonts

FontStruct

FontStruct is a free font-building tool from FontShop. FontStruct lets you quickly and easily create fonts constructed out of geometrical shapes, which are arranged in a grid pattern, like tiles or bricks. You create “FontStructions” using the “FontStructor” font editor. Once you’re done building, FontStruct generates high-quality TrueType fonts, ready to use in any Mac or Windows application. You can keep your creations to yourself, but we encourage users to share their “FontStructions.” Explore the Gallery of fonts made by other FontStruct users and download them or even copy them and make your own variations. You can also use the FontStruct widget to show your FontStructions on your own Web site or blog. Visit Site

Tools

Color

Color Combinations Tester

The Color Combinations Tester from ColorCombos.com lets Web developers test how different color combinations work together on the screen. Simply enter the RBG value for your color or select a color from a pop-up wheel and hit “Set” to save it. To compare more or less colors, you can easily add or remove columns.