GorillaCamPro
Free app with a lot of great stuff. I’ve been primarily using the time lapse and the stop motion. Both of which provide settings that let you control what you get. Also included is a timer, anti-shake, level, and more. Great app, especially for free.
Photosynth
Great app to build something similar to a panorama. Easy to use and creates great colleges of multiple pictures taken together. Even better that it is free.
PhotoFunia
Another free app. Great way to show off your pictures. Simply import your picture, or take a new one, and insert it into one of their premade effects, such as billboards, books, mirrors, and art galleries. Fun.
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artographo
It says it is free for a very limited time. Not sure how long that will be. Photography, cartoon, and watercolor filters provided, with many options within each. Some of the filters require additional purchase. Even without the additional filters, there is enough here to keep me busy.
Auto Adjust
Easy to use. Pull up the photo press a few buttons. Or you can use the sliding scales to create the color/contrast you want. Saves the photo separate from the original.