QTimedRun is an PyQT4-app designed to run as much programs as you like at any time.
It provides you with a calendar and a time widget to pin-point the exact second when you would like a certain app to launch.
You can use it as an alarm clock by launching “mplayer [some file]” or you can use it to launch bandwidth heavy applications after the people on your network have gone to sleep to assure a good ping in the meantime, while not having to do without whatever you want to have downloaded the next morning (the new debian dvd mayhaps?)

QTimedRun is provided under the GPLv2 or later and any patches, whether they add features or fix bugs are welcome at janis DOT blechert AT gmx DOT net