http://ychan.yosc.net/
http://ryoga.heypoorplayer.org/
http://rksa.no-ip.com:8008/~etherstyle/iboard/imgboard.htm (one big /b/, it seems)
http://mooniidx.bemanistyle.com/imgboard/ (i have no idea)
http://www.phylomortis.com/r/imgboard.htm (pretty cool board for hobby game designers with sprites and shit)
http://ctgameinfo.com/fanart/imageboard.php (as bad as it sounds)
http://board.gundams.net/ (a gundam board - obviously)