Mac OS X only: Free application Lockdown is a security alarm for your Mac laptop, complete with remote arming and a security camera. Your Apple Remote handles the arming, and once armed, the application's alarm is triggered by your laptop's motion detectors, MagSafe removal, keyboard or mouse activity, closed lid, or external device removal. When the alarm is triggered, your iSight snaps a timestamped picture and can even email it to you. Based on previously mentioned iAlertU, Lockdown doesn't currently add much beyond a slightly tweaked interface. Neither is foolproof, but a loud alarm in a university library could be all the extra security you'd need. Lockdown is freeware, Mac OS X only.