Now, you can use Photoshop online. Through Adobe Photoshop Express, yet another online photo-editor. But with a difference.
I tested it with Firefox 2.0.13. It's painfully slow in even 2mbps speed. Requires Adobe Flash player. You can find a lot of similarities with Adobe PS, although some of the features were conspicuous by their absence. GUI is good, except it looks a little different than the original PS.
Registration is free. Once registered, you can access your a/c and your edited and saved photos from any PC with online connectivity.
Since it's still in beta, keep your fingers crossed to find out the features yet to come.