You can control your Windows Pc or Mac using your iPhone by the touch pad or Accelerometer:
Use your iPhone as a remote control for controlling Mac or Windows PCs:
Remote Control your iTunes on your Mac using your iPhone:
Touchpad Pro with ScreenView:
It allows you to control your Mac or PC also with seeing the screen on your mobile phone using the touchpad and screen keyboard of the phone.
GyroPhone - iPhone Gyroscopic Mouse
"It allows you to control your mouse cursor with your iPhone like a Wii controller. There is also a touch pad for more exact movements. Works on both iPhone and iPod touch, and the client runs on all platforms that support java (windows, mac, most distros of linux)."