I just found this awesome easter egg that valve put into Portal. Working my way through the game I noticed a login and password written on one of the walls by one of the many "research applicants" before me, but I never found a place to type them in, that is, until Steam's latest update news.
If you go to
http://www.aperturescience.com/ you can watch a Aperture Science, holiday-themed security video and, surprise surprise, a dos prompt! Here's what you do:
(I guess spoiler alert if you want to find the login and password on your own)
1. Type "login"
2. Username "cjohnson"
3. Password "tier3"
4. Type "dir" to see all files
5. Type "apply" or "notes" to select a file
Freakin awesome! The test application is hilarious!