One of my favorite drywall texturing techniques is to put the drywall mud (plaster) on my palm and pat the wall to create little spikes. I let the spikes sit for about five minutes and then carefully smooth over them with a wide drywall knife.
The result is a really cool textured pattern with raised spots and lower spots. Don't wait too long, or the tips of the spikes will get hard and drag little thin lines in the mud when you go over them with the drywall knife. Don't smooth too soon either, though, or the mud will just end up flat with no texture. I texture walls in four foot square sections, and by the time I'm done with the patting on one side, the other side is ready to be smoothed over.