PowerController is an iTunes alarm clock. It is easily configured via System Preferences and offers the following features:

Integrates with iTunes
Plays any playlist you have created in iTunes
Sets the initial system volume and iTunes volume at your desired level
Gradually increases volume for soothing wake experience
Wakes your computer from sleep
Shuts off your alarm if you don't dismiss it after a designated time period (so that your neighbors don't call the police when you go away for vacation!)
Unlimited number of alarms
PowerController runs in the background -- there is no application hogging Dock space
Alarms never need to be rescheduled, even across reboots!
Customizable snooze time
Unlike other apps, you don't need to enter an administrative password every time you want to set an alarm
Optional menu bar item allows easy access to info about scheduled events
Schedule sleep and wake events for your Mac without an iTunes alarm