Tenya, the tempura place, is pretty good. I always ate there when I visited Akihabara. Aside from that, it is mainly an electronics and computer Mecca. Even if you are not anime oriented, it may still be worthwhile to check out the maid cafes just to experience it. There are also gaming centers, if you like arcade games.

The stair comment in that Wiki page is true. The harder to access (and seedier) the place is, the better the prices. Anime goods are really a must buy there. Gundam models are dirt cheap too.