In our couponing/coupon train forum, some members used to offer up pot luck envelopes to free up some of thier coupon stash. I can't say members really do that anymore, but I do know that some occassionally now offer them up in the RAK forum. You might try in there.
We also used to do TAGS, this was a potluck of sorts. You would offer up a potluck envelope, and say 'Who wants it'. The next person would then get it, take what they wanted, refill it, then offer it back it. It was a 'tag your it' type of system. It was on the same idea of a coupon train but you never knew where it would go next. We stopped doing that a while ago, when we revamped coupon trains and cleaned up the forums I think.