The clone stamp tool allows you to copy (clone) from a target area in a photo and paint it in to a destination area with regular brush options.
Clone stamp is perfect for minor retouching on the seams of areas that have been cut and pasted together.
Here are some great images made entirely in Phoenix that used elements of the Clone Stamp Tool:
Colin Farrel & Tara Reid merged by Meowza
Street by phischer
From the "People are falling apart series" by Meowza
If you already have a Phoenix account, you can open up these images to see how they were made and try editing them further!]]