Yeah.. Just go through iCal. You can put together a workflow in Automator to have it start playing something in iTunes with:
1. Get Specified iTunes Items
2. Start iTunes Playing
Save this workflow as a Plugin for iCal Alarm.
In iCal, set it to the time you need it to go off and make it a repeating alarm.
If you want to put the computer to sleep at night, you can schedule your Energy Saver to wake the computer a few minutes before the iCal alarm is set to go off.