Take a photograph or website snapshot look like a piece of paper that is laying down.
Just for fun, speeddrawing a fire breathing cat in outer space with a lightning bolt.
Accurately straighten a picture that is a little tilted. Use the measure tool to find the correct angle that you need, then rotate the picture by that angle.
Interpolation is a useful way to change from one shape to another across distance.
Make characters look like they are sticking out of the picture frame.