How about running some demo programs that showcase what the Pi is capable of? Awesome graphics, anyone?
Raspbian comes with a range of demo programs which you can just compile and run. They range from simple hello world text output, to full 1080p HD video playback, 3D spinning teapots and real-time animating fractal patterns. These are a great way to get a feel for what the Pi can do, and to gain some familiarity with navigating around the system and running programs at the command line.