Macworld has a useful short article based on an interview with Glyn Evans of iPhonography.com. It's a top website if you're into using your iPhone's camera to take photos. And during the interview, Evans identified his six favorite photography apps. They include Perfectly Clear ($2.99) which automatically sharpens and brightens your photos. AutoStitch Panorama lets you create panoramas, and other apps let you turn photos into black & white and then selectively adding color.