An American-based seller (that Iolaus showed me to help me score major points last year with the wife) of all sorts of alcoholic beverages is High Times Wine Cellar. They have stuff that I didn't even know was available in the US until I visited them.

Example: Jennifer (my wife) fell in love with Bunnahabhain while we were in Glasgow in early 2004 and we were told that we couldn't get it in America. Well, I found it there... and Jenn got it for our anniversary last year!

Check them out.