iPhone: Camera+ has long been our pick for the best camera app on the iPhone, but people always lamented about having to shell out $3.79 for it. Now there's a free version that seems to pretty close to the paid app.
The version allows you to change exposure and focus easily, shoot in different modes, has a number of effects and scene modes, and has a digital zoom that will get you a lot closer than the default camera zoom. It's lacking some stuff though. For example, the Lab, where you can dig into manual edits (and includes their much touted "Clarity" adjustment), is a paid upgrade.
Still, there aren't any ads or anything, so if you're just looking for a nicer camera app and don't want to spend any money, Camera+ Free does the job. The paid version should be getting some fancy new features in the future to make it more worth the extra cash, but we'll have to wait to see what they are.
Camera+ Free (Free) [iTunes App Store]