This is one of my favorite apps and the most expensive one that I own. It's robust and offers many ways to enhance, tone and manipulate images. The auto-correct option is a one-touch way to quickly add contrast/sharpening and vibrancy to any image. If you have more time, it offers pinpointed tone adjustments, cropping, sharpening, selective focus and additional options to grunge it up. If you're familiar with photo-toning software for your computer, this app is similar in its robustness and options.
Great for capturing panoramics of the settings around you. It's easy to use, saves high-resolution images to the Camera Roll and offers the option to crop the final image. If you have a Facebook page, then you've seen pages with a panoramic image across the top. AutoStitch is the perfect app for creating an image for this design.
Diptic (99 cents)
Allows you to combine multiple photos into one image using any number of pre-loaded layouts. If you took three beautiful shots, consider combing them into one image and using each frame to highlight the different details that caught your eye. You don't have to use separate pictures; you could use the same photo but zoom in on different details in each frame. With a little bit of creativity, you can use Diptic's multiple frames to tell a story or show action the way a comic-book artist might. To use it, first select the layout you want, then tap each frame to load your photo. Zoom in by pinching or stretching the picture.