I learned this last week that in Windows Vista one can hold down shift and right click to get a "Command Prompt Here" option added to the context menu on a folder. Nice!
-- Ari Pernick
Update: As someone in the comments noted, "Copy as Path" gets added to the context menu too. I typically click on the address bar and copy the path that appears there, but I think this trick is faster if I can retrain myself to use it :).