This one is PERFECT for what you are looking for.
-Free
-As many alarms as you want
-light-weight app
-choose songs/videos/shows/anything from you iTunes library as the alarm
-Wake from sleep
-Fade in from customized sound level and get louder until whatever percentage volume you desire
-Snooze
-Set alarms to happen repetitively one certain days every week
-Timer
-Stopwatch
-Updates
-Apple remote compatible!
-MORE
http://www.robbiehanson.com/alarmclock/
The original page is no longer available. You can get the latest version from MacUpdate:
https://www.macupdate.com/download/20597/Alarm Clock.zip