The stuff people put in their pipes, yeesh... rice, sour cream, camel excrement...I've read somewhere about using rice in the bottom of the bowl to absorb moisture. I bet it's a surprise when one gets to that, too!
Rather than rice, one can use much cheaper tobacco like that intended for RYO. It tends to be very dry and readily absorbs moisture and tars from the tobacco burning above it, acting as a filter of sorts and prevents wasting the good tobacco. I do it all the time.