Startup and Shutdown Screens

Akertyne Arts
Animated startup screens for Windows.
http://akertyne-arts.netfirms.com/index22.html

MetalScreens
Heavy metal startup/wait/shutdown screens for Windows. Also offers desktop themes and screen savers.
http://www.angelfire.com/rock3/megabob6666/

Planet Mainstream
Many start-up logos, with instructions on replacing the Logo.sys file.
http://www.angelfire.com/my/plinth/logos/logos.html