Yesterday morning, I spent some quiet time on the couch reading my BH&G magazine and they had a great article about photos and apps. They recommended the camera+ app, so I bought it (I'm an easy sell). I've been testing it out and so far really like it. It's somewhat similar to Instagram but has this cool clarity function that enhances colors. Basically everything is a lot brighter and truer to color than without it.
Here's a shot that I took with my regular camera phone
Not too big of a difference, but it does have a zoom feature and grid so that your photos don't come out crooked (see aforementioned photo). Though, I think it's grainier.