Have you ever wanted to see what Microsofts newest software is like, but don't want to muck up your current system? Visit the Microsoft Download Center to download some Virtual Hard Drives of their newest (mostly server) software. You will need to have Microsoft Virtual Computer to enable these Virtual Hard Drives.
Via the link you can test out Microsoft Server 2003 R2, Microsoft Exchange Server 2007, Microsoft Internet Sercurity and Acceleration Server 2006, and Microsoft SQL Server 2005.
For me this is awesome because it allows me to play with this new software before I see it in the enterprise and allows me to become aclamated to it before I start studying for it's certification. Also the temptation to pirate software is no longer there for many IT professionsals since they can get their hands on it legally now.