I'm still a newbie, so my apologies for my ignorance. I was browsing the CCGTCC glossary to familiarize myself with some of terms and saw...

ROUND ROBIN: Similar to a chain letter where packages of chips, slot cards, tokens are sent to collectors who have voluntarily signed up in advance to a distribution list for the purposes of trading. When one item is removed from a Round Robin to add to one's collection, it must be replaced with a different item before sending on to the next recipient.

Do these actually exist? What an interesting way to expand a small collection and have little surprises waiting for you in the mail when you get home from work.