I have seen a couple other forums do it and it ends up being a lot of fun. What you do is you go out and get a Flat Rate box from UPS (which ever one is designated) and you go around your garage and fill it with items you don't need anymore or want to give away. Then you send it out to who ever you get assigned, and someone will get assigned to you and you will receive a box as well. Then you can leave a note explaining what is in the box and what not. For example, my friend participated in one on his Subaru forums and when he received a piston from a EJ25 motor that he made into a door handle, a couple of magazines from late 90's with Subaru stuff, a T-shirt, a shift boot, a couple of intake couplers, etc. He ended up sending his person a throttle body he had laying around, a Subaru banner he didn't want anymore, a poster with a cut away of an EJ20, and I think a couple candy bars.
You don't put in just junk no one wants, but you just throw in a couple things laying around your garage. If you guys aren't interested or think it sounds stupid, I understand because its hard to explain. But a couple of my friends do it with their forums and they usually have a blast.