iTeleport isn’t cheap and is more than a little geeky, but it’s so cool and potentially useful. iTeleport is technically a VNC (Virtual Network Computing, also known as remote screen control) client. Put another way, it’s an iPhone app for controlling your Mac, Windows, or Linux computer from a few feet away or from halfway around the world.
Yes, you can actually see your computer screen and control its keyboard and mouse from anywhere in the world (as long as your iPhone can connect to the Internet through Wi-Fi, 3G, EDGE, or whatever).