Mac OS X only: Wake yourself and your Mac with freeware app Alarm Clock 2. It boasts tons of features like repeating alarms, “easy wake” (the volume of the alarm slowly increases), wake to music or podcast and customisable snooze duration. The two most appealing features of Alarm Clock 2 are that it also comes with a countdown timer and a stopwatch, and that prior to activating, Alarm Clock 2 will also bring your Mac out of sleep mode. You might also want to check out the popular Mac-only alarm clock Aurora or web-based alarms ALARMD and the Online Alarm Clock. Alarm Clock 2 is a free download for Mac OS X.