Yet another company putting out a map of shops in Akihabara is Otamap, an otaku-themed advertising forum. There's really no difference here between Otamap, BIZS and ASCII Weekly. Primarily it's just a question of which shops paid to advertise through which agency.
However, Otamap's website does have a fairly complete map for Osaka, which does set it apart from the other two, which are Akihabara-centric. And it does list upcoming events for doujinshi at Big Site, and anime releases at other venues (Japanese only).