Akihabara used to be a mecca for electronics. A place where you could buy anything from a television set to a 15 ohm 25 watt resistor.
It's still the place where electronics geeks hang out but I noticed a big change from the retail to services sector when I last visited. Lots of internet cafes, lots of stores selling manga, porn, etc.
Check out the @Home Maid cafe if you visit. It's very entertaining (for both males and females) and it's probably worth the visit to Akihabara alone.
