Well.... for a little while I was using cat litter as flocking material. 
That particular technique was talked up a lot a few years ago in several of the miniatures mags stateside (MWAN, the Courier, etc.); it does work well. I always thought it was funny, though, that virtually every article discussing it, letter mentioning it, etc, made sure to use the disclaimer, "DO NOT USE DIRTY CAT LITTER".
I just -know- somebody was loading up his bases with glue or paint and then dredging them through the catbox...

-Doc