(Last minute) things to do in Seoul

[PhillT]

Hello. I've found myself in Seoul, with a free day for most of tomorrow before my flight. I've been to the Royal Palace and the Seoul Tower - anyone got any other recommendations of things to see or do?
Wanted to go to the DMZ but it seems you have to book in advance.
Cheers!

[PhillT]

Obviously not a common destination for the board-dwellers, but should anyone else stumble on this thread while at a loss of things to do in South Korea, I went to the Korean War Memorial museum, where I spent a very interesting and educational few hours learning about how the Japanese keep invading and the North Koreans are quite sneaky. Also, lots of guns, planes and boats to look at.
As an aside, the Hongdae area of the city is highly vibrant of an evening thanks to the sizable student population. Recommended and not as seedy as Itaewon. Fewer US servicemen on the lash too.