In the run-up to the Stampin' Up convention, most of the organized swaps fill up FAST! Sometimes the host will open another group--but the more groups, the more unwieldy the swap becomes (and the more nightmarish the whole things becomes for the host). Sometimes hosts will open a waiting list where the late-comers wait in hopes some other swapper has bitten off more than he or she can chew and have to drop out. (You know, like signing up for too dang many swaps!) The wait listers know a bit prior to the event whether they will or will not need to make cards for the swap.
And sometimes, the host asks for "angel swappers." These are swappers who make the full contingent of cards and wait at the swap site in case someone "flakes"--forgets the time/place, decides they didn't want to participate, missed their flight into Salt Lake City (hey, it happens). The angels may or may not get to swap, even though they've done all the work. Awww!
I volunteered to be an angel swapper for Lyssa Zwolanek's convention quality swap. I've made up a set of cards just in case someone in another group "flakes" and can't fulfill the obligation to make all the cards. I might or might not get to swap these cards in the CQS swap. I can use them as "general" swaps in that case.
You may recognize this card. It's based on this one. I liked that design so much, I CASE'd myself! But this time I added the globe from the Traveler set and the "hello" banner from the Perfect Pennants set.