In April 19, (2012) Picnik is closing its website completely.
After being acquired by Google in Mar, 2010, the service was active for two years, and soon will join Google+. It’s good news if you use Google+, but probably bad news if you don’t. I was, and still using Picnik editor constantly to improve pictures and screenshot, so of course I just had to find good alternative. Surprisingly, Befunky does the job just fine. In fact, it has more tools and filters than Picnik ever had, and you get a lot more for free. If you never used it before, you should definitely give it a try.
Befunky has a long list of edit features where you can crop, rotate, resize, sharpen, and just about every filter you can think of to make your photo look amazing. You can than save it, share it, print it, and all of this before you even signed up to the service.
On top of everything, Befunky has a long history of applications for pictures (mobile included), this is their specialty. It is a reliable service, with very easy to use editor, tons of options (really, never seen so many on one service), and most of it is free – Can’t think of any reason why not using them as your primary photo editor.