Gizmodo has a great list of 8 advanced photo editing techniques for the iPhone.
You might already be familiar with the quick fixes you can apply to your pictures after you’ve snapped them, right on your phone—but if you want to take your mobile photo editing to the next level there are tools and apps that can help here too.
The editing techniques include: Combining photos together (compositing), removing objects from photos, adjusting the depth of field, adjusting white balance, brightening shadows, healing, correcting image distortion, and photo pixelation.
Check It Out: 8 Advanced Photo Editing Techniques for iPhone
Hmmm, by the title I assumed that the techniques were available in Photos.