If you're into imports that is. I've seen 3 non-consecutive requests on different boards (one here) of "where to go shopping in Japan". I put together a Flash map of Akihabara. It's by no means complete, but is a good start I think. I've put some of my opinions of each of the shops as well.
It includes console game shops, arcades, and PCB shops.
Enjoy
http://dynamic5.gamespy.com/~japangaming/akimap.php