Nik Software Inc. Snapseed App
From the Editors of Freeskier:
Turn mediocre cell images into Instagram gold with Snapseed. Use Details/Structure to up clarity, Selective Adjust for delicate tweaks or Vintage for a retro feel. The possibilities are myriad. It’s the best photo editing app in the game. (iPhone 3GS, 4 & 4S, iPod touch 3 & 4G and iPad. Coming soon for Android.)
The Cons: It’s a bit tricky to figure at first. Just experiment.