I use a service called Zunafish which allows their users to trade CDs and DVDs and other items.  Once a trade has been agreed upon, each user is charged $1 and then whatever the shipping charges for that item.  More often than not, when someone proposes a trade, I'm not interested in what they have to offer. 

Someone who offered me a trade this weekend had 4 interesting DVDs in their collection that they're willing to trade.  Can you guess the theme this person is fixated on?  Either they are ridding their collection of this subject or this might be all they have.  Or, a parent is selling their goth kid's DVDs now that they left the house.  Needless to say, I went with someone else's offer.