It's called ipiccy.com
You begin by uploading your photo. Just click and begin experimenting. Think Photoshop... but simplified. Anything you might want to do in Photoshop, you can do with ipiccy.com. There are the standard editing tools from cropping, blurring, changing the colour balance etc. to the fancy - turning your picture into a cartoon image or wanted poster. The possibilities are endless.
I use ipiccy.com with my class all the time. This site is definitely worth exploring (and using)!