PowerController for Mac

From Sanity Software:

PowerController is an iTunes alarm clock that is simple to use and packed with amazing features:

• Wakes your computer from sleep
• Integrated with iTunes
• Plays any iTunes playlist
• The initial system volume and iTunes volume are customizable
• iTunes alarms can have a gradually increasing volume for a soothing wake experience
• PowerController can shut 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 a long weekend!)
• iTunes alarms and wake events can launch an application, open a file, or run a script
• Set a different wake time and playlist for every day of the week!
• You may schedule an unlimited number of events
• PowerController runs in the background -- there is no app hogging Dock space
• Configurable via System Preferences
• Admin password is NOT needed to set an alarm that wakes computer from sleep
• Snooze feature
• A status item may be kept in your menu bar for easy access to info about scheduled events
• Free, unrestricted 30 day trial

PowerController can also be used to schedule times for your computer to go to sleep or wake up (without an iTunes alarm).