I had downloaded Autodesk's Pixlr-o-matic Android app to my Samsung Galaxy S a few months ago but never really used it. For some reason I decided to have a go with it tonight and it's not too bad. It's not subtle by any means in regards to post-processing but it's kind of fun.
Not sure if it will replace my main camera app which is Vignette for Android but it's a nice app to have on the side along with Snaptastic.
You can download Pixlr-o-matic for your Android or iOS device, it's free. You can also use it through your browser by going to pixlr.com/o-matic.