I don't have that many apps on my phone, I suppose I don't really use my phone properly. I do, however, have a little gem of an app called 'Vintage Cam' which I probably use everyday. It's free, and very cool. You take your photograph and then you can change the effect. Below are some of my favourite snaps I've taken using Vintage Cam-
Definitely an app worth getting. Oh, and they print quite well too.