If you get a chance, go to shinatatsu in shinagawa and eat at the northernmost ramen place. It's easy to find: take the west exit of the shinagawa JR station and follow the sidewalk south, because it's sorta under the train tracks. Here's a picture: http://www.flickr.mud.yahoo.com/photos/ishiguro/2550364/
Oh man is it good. Expect a bit of a wait to get in -- you'll recognize it by the long line of people in front. The second one (just south of the northernmost) is pretty good too and doesn't have as much of a wait. You may wanna bring a Japanese speaker because they don't support English there.