First up is the coolest app of them all. Microsoft recently released , an app that lets you create "synths" using just your phone. In a nutshell, Photosynth takes a collection of photos taken around the same location and, sort of like a traditional panoramic program, stitches them into a coherent scene. A Photosynth image can be 360 degrees and interactive, though--you can pivot around the scene from the point of view of the photographer, looking up and down and all around, and zoom in for a better view.

Microsoft's Photosynth for the iPhone delivers all that in the palm of your hand. The app lets you take a slew of photos and then stitch them together. You can take just a few shots or diligently fill in every corner of your surroundings. Photosynth shows you what regions are captured and where the gaps in your scene are even as you shoot. When you're done, it takes a few moments to process, and then you can interact with your synth on your iPhone or upload it to share your handiwork. It's all free--and it feels a little like science fiction.

When Adobe first released , I thought it was a bit of a curiosity--a fun diversion, but not especially practical or useful. These days, Photoshop Express makes it possible to clean up your iPhone photos in a meaningful way. Of course, Photoshop Express doesn't include any of the goodies you'll find in CS5 or even Photoshop Elements--there's no support for layers, masking, background removal, or those sorts of things. Then again, what do you expect? This app is running on a phone.