Recently Chris Sells posted about winfx.com and how it redirects to the Longhorn Developer Center. As someone who doesn't really use Favorites this is a great shortcut to have. Just type “winfx” in the address bar, hit Ctrl+Enter and you're there.
Two other domain name shortcuts I know of are wmlah which leads to the WatchingMicrosoftLikeAHawk site and msdn which finally leads to the Microsoft Developer Network site. I say finally, because this is a recnt change. I know that for at least a year the domain name “msdn.com” was owned by a third-party he just posted a link to direct you to the Microsoft MSDN site. I wonder how much that guy made when he sold the domain name…
Do you know of any other shortcut domain names I'm missing?