LogMeIn Free and LogMe In Pro are Windows and Mac compatible programs for completely controlling your computer with just an internet connection. Once you log in, your browser will looks just like your desktop remotely!
They've taken it a step further by bringing it to the iPhone and iPod Touch with the new program LogMeIn Ignition. This means you can have the same level of control, except instead you're seeing and controlling your computer from anywhere with a decent internet signal. Ignition can be stored and run on any PDA or flash drive. Just plug the drive into a computer and connect without any installation.