I've become a shogi fan in the few games I've played, and recently found that there are many smaller and larger Shogi variants that look extremely intriguing to play. They range from the absurdly small (4x4 "nana" shogi) to the absurdly large (taikyoku shogi on a 36x36 board with 402 pieces per player). I'd be interested in both ends of the spectrum and all those in between, but there are a few that are especially intriguing:

Chu Shogi (12x12) - a good size, I think, and has an active following worldwide
Dai Shogi (15x15) - very large, but perhaps playable in a few hours
Daidai and Maka Daidai Shogi (17x17 and 19x19, respectively) and Tai shogi (25x25). some of the smaller variants sound interesting as well, and they range from 4x4 up to 9x9.

Would there be interest in getting more Shogi variants on BK? I'd vote for Chu and Dai immediately.