I put up a mailing post card on our local Whole Foods bulletin board and everywhere else I see I can put one up! I also PLACE my biz cards in those 'win a free lunch' glass bowls - but I slide my card down the front so they show out of the bowl.
I've never gotten a call specifically from one of these placements BUT I have been told by several people that they've seen my logo somewhere - not sure where - and it looked familiar when they got my mailing piece which is why they called.