There are plenty of iOS camera apps out there — an App Store search yields over 12,000 results. While most of these are just a refactoring of the same tired ideas, Mextures ($1) does things differently. Like a lot of camera apps, it includes a library of original textures, including gradients, grunge, light filters, and film scans (70 in total). Unlike other camera apps, it allows you to combine different textures on separate layers, using blending and opacity to create an original style. Once you're happy with your combination, you can save it as a formula to reuse as much as you like.