Well if you want to just upload a your own and edit i use www.fotoflexer.com
www.lunapic.com/editor
http://www.picnik.com/app
To see others:
Live Journal.com has a lot of different groups where you can look at other peoples pictures. Also their is photobucket which I'm pretty sure that you probably knew that and flickr is the only ones right now i can think of.
