http://advanced.aviary.com/ 
This was a decent site but could of been better. It didn't have the tools i would of liked and some of them were hard to control.
http://pixenate.com/
This was almost the same as the first site and it didn't have the same tools as picnik.
http://www.lunapic.com/editor/
This site was better than the first two but still wasn't as good as picnik.