Lockdown is a donation-ware app that can help you secure your Mac against physical tampering. It disables your Mac to would-be intruders by sounding an alarm whenever a variety of user-specified triggers is set off, including your Macs motion sensor. It also can lockdown the keyboard, mouse, and other external devices, or--for MacBooks--your lid, trackpad, or MagSafe adapter.
Lockdown sounds a loud alarm and prevents your Mac from being put to sleep or muted, and it can also take and e-mail a picture using your iSight camera. Lockdown is most effective by far when combined with an Apple Remote, which lets you quickly activate and deactivate Lockdowns alarm with the Menu button. Lockdown requires Mac OS X 10.5 or later.