the elusive scroll lock key.

[osaraba]

If you want to see what it does:
http://members.aol.com/elmothecow/scrollock/scroloff.htm

If you would like to know what it really does:
http://www.straightdope.com/mailbag/mscrolllock.html

If you would like to be able to use it, for real:
http://www.scroll-lock-lives.com/