One of the best ways to control your Mac with your iPhone is Remoter. The app is pleasantly easy to set up. The Remote Desktop app (VNC) teams up with the Screen Sharing function build into Mac OS X (have a look in your system preferences under sharing). You can open/close applications or move files among many other things. Using Bonjour you’ll have your wireless desktop control running in seconds. Connecting through the Internet is slightly more tricky. You can find a tutorial over here. For $1.99 (currently 0.99) it’s a bargain!