Photo Stats is a cool little US$0.99 iPhone app that provides statistics on your photo-taking habits, like number of photos taken, storage they occupy, frequent shoot locations and more. While none of the supplied information is of the "mission critical" variety, I found them interesting. Your compiles stats can be shared via email or Twitter.
Photo Stats also tracks the time of day you're most likely (and least likely) to shoot, the frequency of portrait vs. landscape mode, ISO settings, shutter speed and more. I actually saw some things that will help me improve my pictures. I have lots of low light images, and don't usually use flash. It seems obvious, but I never think to turn it on.
I like apps that collect and present information in an interesting and "hands-off" way. One thing I'd like to see added is a way to create these graphs from albums other than the camera roll. It would give me more data and therefore more information to evaluate my images.
The UI is well done, and sometimes there are comments about my photo habits. Photo Stats is clever, and not a big investment. The app runs on an iPhone with iOS 4.2 or later. It runs on the 4th generation iPod touch, and the iPad 2. Check the gallery for a look at some of the graphs.