Just a general Tokyo suggestion, if you like Electronics, you have to go visit Sony! You can walk through and see all of the newest electronics that haven't been released outside of Japan yet.

Other than everybody's suggestion about the New York Grill, I can't think of any *must eat* places in Japan. One of my favorite ways to eat though (and I can't think of the Japanese word for the type of establishment) is going to those bars that you can order different meats grilled on skewers, and drink little beers. Take some friends and spend a few hours!