Serendipity35

I was looking for some online apps that allow my students to edit images. Not everyone has software available and I wouldn't recommend the Photoshop route for beginners (cost + complexity).

Earlier I had recommended PXN8.com which allows basic image editing online (no download required) and then you can save your changes or directly upload them to Flickr.

Recently I discovered Picnik which also allows you to fix underexposed photos, remove red-eye, apply lots of effects,crop, rotate, and resize in real-time. It works directly with many photo sharing sites on Mac, Windows, and Linux. There are free and premium versions.