PicMonkey

 Regular oatmeal with blueberries.
Had-too-much-coffee-before-my oatmeal with blueberries.
You'll find effects, tools, and more with the ever-so-awesome PicMonkey - a free online photo editing and effects site from some of the former Picnik developers. For a chuckle, have a peek at their "About" page. Need a review before you swing on over to play*? Try this one at the Photo Software Blog.

* When you swing on over to play, be sure you've got some time. I found myself investigating the various tools and trying out all the effects and quickly lost an hour. Neat effects, and pretty easy to use!