Isn't a Kusari-gama an exotic slashing/bludgeoning weapon with reach that a monk may include in his list of special weapons when he gains the exotic weapon proficiency for it? I know the slashing end is 1d6 while the bludgeoning end is 1d4 and you get to choose which end you may attack with, or you may lose reach and use it as a double weapon. Plus you may trip with and it has a +2 disarm bonus, and you may apply weapon finesse to it.

I can't remember which book it is from though.