NOTE: When adding useful contributons to this thread, please just batch a few programs into one single post, so that future referals to a certain program mentioned in the thread are easier to follow.
Also please ONLY add freeware programs!
Logon Loader makes swaping logon screens easy.
It can randomly select a logon screen every time you log on.
http://logonloader.danielmilner.com/
Shuts down specified process when another specified process starts. This is extremely useful in case you got something resource intensive running, like samurize, coolmon or any of those dock programs, you you suddendly feel the urge of play Doom 3 (or any other game). Game Starter will shutdown samurize coolmon or any process you specify when it detects a game running. When you exit the game, it starts them again, as if nothing happened. All this is done automatically, all the user has to do is to specify the processes.
ftp://seagulls.mine.nu/GameStarter.msi
http://users.pandora.be/jbosman/applications.html
Poweroff is a small program for Win95/98/NT/W2K/XP to schedule a shutdown/reboot/logoff/poweroff/Standby/Hibernate/Lock/Wake-On-LAN at a certain time. It also supports command line options that allows poweroff to be used in batch scripts. It has a built-in scheduler, it allows you to run a program before doing the action, you can give a warning message to the user, wait for a process to finish before doing the action and full remote control is supported.