Focus 2 (US$ 11.99) is a useful Mac photography app that probably does the opposite of what you might think from its name. The app isn't designed to focus your images, but rather de-focus them so you can direct the eye to the portions of the photo that are really important. The app simulates what special lenses can do on your camera, but with Focus 2, it's possible to endlessly adjust and refine focus effects rather than just get one chance with a single photograph or two.
You start by dragging a photo into the app, and then selecting from macro, tilt-shift, portrait, nature or architecture tools. You can move and rotate the focus point around to get the effect you want, straighten and crop images, add vignettes and adjust aspect ratio. There is also a one-click enhancement feature that changes contrast and saturation to improve some photos.
The app works just fine. I actually found more photos in my collection were enhanced by using Focus 2 than I expected. Photos can be sent directly from Focus 2 to Photoshop, Aperture, Lightroom and iPhoto. Focus 2 supports RAW files, and has been updated for Mavericks. Changes of focus are fast, and tapping the space bar on your keyboard reverts to the original image. In portrait mode, face recognition helps the placement of the focus points.