Sweet Dreams is a tiny shut down timer for your computer. All you need to do is select the duration between 5 and 120 minutes, and the action to be performed: shut down, switch off monitor, standby mode when the time is up. During this time the volume level is being reduced down to a selected level... "Sweet dreams!"
alt text http://cache.gawker.com/assets/images/lifehacker/2009/04/sweet-dreams.png
Sweet Dreams is freeware and portable. (using the actual version 1.21 in Windows Vista/7 requires "compatibility mode for XP")
Strange, version 1.1 works fine without compatibility mode in Windows 7, probably because it doesn't feature hibernate/standby, just shut down (which suits me fine).
alt text http://i365.photobucket.com/albums/oo94/eeemolly/sweetdreamwin7.jpg
Here's a direct download link for Sweet Dreams v 1.1.