Here's an article on PicMonkey that you can read: Article
I really like the features available on PicMonkey. I think it is easier to use than Picnik and there is no need to register to use the features. All you need to do is to upload the photo, edit it and then save it back to your local drive. Your photos are never publicly available and you retain the copyright to your image. All in all, I feel pretty safe using this website.
I've done a couple experiments on PicMonkey and here are the results:
|My adorable niece in "Cross Process"|
|Pastry in "Polaroid"|
|Old Bank Arcade (Wellington city) in 'Tranquil'|
|Grandpa in "Lomo"|
|Matryoshka dolls in "Urbane"|
|Chinese cake in "Urbane"|
|Ice cream in "intrepid"|
I really love the results. It's one of the ways I can take advantage of the special effects for photos without needing to buy a smartphone and downloading Instagram. After all, I only have a Sony Ericsson brick phone!