If you love anime and manga, Akihabara is the place to go!
There are lots of shops where you can buy manga and DVD's, and on the streets there are anime-banners and huge screens everywhere. There are also big game centers where you can play all kind of games. For example, fighting games like "Tekken" or music games as well.
It's very impressive to see but also really crowded.
Find everything from idols to electronics in Akihabara