I have been experimenting with the application Picnik and it's AMAZING, especially when using the Firefox plugin. For someone like me who doesn't own Photoshop but still likes to play with and alter pictures (presentations, blogging, etc) Picnik is a God-send. It allows you to screen-capture, or directly upload images for editing. Once uploaded you can then save directly to Flickr, Facebook and other sites. The customization features are cool as well - definitely not as in-depth as the expensive programs - but for a FREE, web-based image editor I have yet to see anything that matches it. Oh and it looks super cool too.
Picnik has been gaining steam as a result of its integration with Facebook's F8 platform. Definitely try it out or read some more reviews.
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