Renaissance Festival
Went to the Maryland Renaissance Festival this weekend. I strongly recommend it to anyone who's in the Baltimore/Washington area. It really is an amazing spectacle. There's scheduled entertainment going on all the time in 8 or 9 different areas, as well as street theater, glassblowing demonstrations, jousting, and tons of shops. It's great fun, but be prepared to do a fair amount of walking, since it covers a lot of ground.