I'm going to link to Larry Ferlazzo's post about photo editing tools. He talks about Wylio and ImgOps.
While I'm at it, a user review of another website I stole from Mr. Ferlazzo. I've mentioned the website CutMP3 before as a potentially interesting piece of software. I haven't had a chance to play with it, but one of my students (at my recommendation) used it in a "book soundtrack" presentation. He said that it was easy, took him not much longer to do than just assembling the playlist would have, and played back perfectly in Windows Media Player. No word yet on whether it plays in iTunes, but my student gave me all of his source files. Mac tests are forthcoming.
Incidentally, Mr. Ferlazzo cites TechCrunch as his original source for the picture-editing software. I think I'll try following them for a little while, too.