TiltShift Generator, Free!
One of my favorite lenses for my SLR is the Lensbaby I picked up on a whim a few years back, and TiltShift Generator does a brilliant job of re-creating that for the iPhone. If you are unfamiliar with the effect, basically what you are doing is choosing a spot of focus that the image progressively blurs out from. TiltShift Generator gives you the option of using a focus that is a straight line or a circle (like the Lensbaby). You can adjust the amount of blur, making for a photo with a very specific focus and a lot of blur or a mostly crisp image that has blur near the edges.
A lot of apps are one trick ponies that will let you apply a filter but not crop or adjust brightness–TiltShift Generator is not one of these. Besides the blur adjustment, you are also able to make changes to saturation, brightness, contrast and vignetting. I just wish there was a crop/zoom feature.
The fact that this app mimics one of my favorite real-life lenses makes it an instant win for me, though it is an aesthetic choice that not everyone loves. There is a free version of this and a $0.99 version, and according to iTunes the only difference is the exported image size and album import features. I’m not particularly concerned with either of these, so I have the free version.
(this photo uses the circular focus at the center of the flower and a fairly small amount of focus as well as a heavy vignette and some increased brightness and saturation)