The Smithsonian's on Twitter

I just started following one of these feeds in Twitter, and it turns out that this group of museums has a ton of Twitter feeds: http://www.si.edu/Twitter/default.htm. I thought this might helpful to those exploring D.C . The U.S. Holocaust Museum is also on Twitter: http://twitter.com/holocaustmuseum in addition to the Library of Congress http://twitter.com/librarycongress.

Anyone have any other DC related feeds to add to this list?