I really enjoyed Color Splurge. I wouldn't have found this app without 23 Things. There are so many out there, that unless you know what you are looking for you sometimes miss out on fun, useful ones. And it's ones like CamMe that make me envious of Apple products. (I'll have to tell me husband about this one.)
I often use Pixlr.com on my desktop. I do also like the Pixlr-O-Matic for fun, styled photos.