...for instance:

Let's say Terry Shaffer likes one of the groups of cards I'm offering. He checks his traders and finds a whole box of chips he's willing to give up. So, he posts a reply to my offer, accepting free slot card group #7 and he posts a scan of a dozen chips, offering one of them to the next person who wants to continue the chain...

...If anybody else sees some of my slotcards they want, they can post their own offer. The one lot of slot cards I'm offering will go to whoever gets somebody else to accept their free stuff first. This provides incentive to offer the best stuff that will get accepted the fastest.

...so Mark Englebretson see's the chips Terry posted and decides that his daughter needs one from Deadwood for her new collection. So he checks the stacks and stacks of ashtrays he has and finds one he's willing to part with. He posts a message accepting Terry's offer and posting a scan of a highly polished ashtray free to the next person who wants to continue the chain...

....Once Mark Englebretson posts his acceptance of Terry's offer and makes his own offer, I close my link in the chain and send the slot cards Terry selected to him....

....Jill Bitner pulls herself away from her landscaping long enough to check the Chip Board and sees that Mark Englebretson is offering a Harrah's ashtray she doesn't have (yeah, like THAT'S gonna happen). So, she checks her traders and pulls out a group of matchcovers, scans them and posts her acceptance of Mark Englebretson's offer and her own offer to continue the chain....

....Once Terry sees that Jill has accepted Mark E's offer, he closes his link in the chain by mailing Mark E the Deadwood chip....

....and so it goes....