Replace the Leopard's login screen background!!
Simply replace this file:
Then use Disk Utility and run "Repair Disk Permission" (Yeah...I'm too lazy to type in Terminal to fix that)
*Digg users: I'd had never expect this page will show up on digg front page!
(May be everyone hates the default Aurora.jpg and they want to change it! /sarcasm)
PS. This is a very little tip for Leopard users; could you guys stop mentioning other OS because this post does nothing with them? ;)