Okay, I probably could suggest to yall stupid little freeware programs to do this, but as an Unix/Linux fan and digging through stuff that makes mac's tick, is.. well.. Fun!

So, here's the scoop.

AppleScript - This program is bundled with OS X which lets you record and run actions. Or make script-based programs.

Well, This is what you do. Open AppleScript

Go File, Save As

In the "save as:" area put something like "itunes sleep timer"
Where: wherever you want, so you can run it easy
File format: application
Options: uncheck all

hit save.

Paste the following in:

CODE
tell application "iTunes"
    delay 3600
    quit
end tell


Hit "compile" then hit save, then close it. When you run it, it will run as a blank program, no window nothing, but after the "delay" expires, it will close iTunes.

The great thing about this is where it says "delay 3600" you can change the delay to however many seconds you want the program to run. I have 1 hour (takes bout 30 minz of sitting for me to pass out).

You can also customize the application to make a timer for whatever app you'd like.

Cheers