I seem to have discovered swap-bot, a site which organises swaps between people.
I found it while idly googling for “we swap snacks”, while waiting for assignments on the recent we_swap_snacks swap. (Signups are probably still open due to the low number of participants by the original date! Join now so that we have a goodly number of participants!)
The main focus on swap-bot seems to be on swapping arts and crafts (I got bombarded with a whole host of terms I had never come across before, such as “ATCs”, “twinchies”, and “SMASH books”) but also has frequent swaps for postcards (which is right up my alley given my long involvement in Postcrossing) as well as other things—including the occasional snack swap and a number of electronic-only swaps such as blog followers, profile comments, or uplifting emails.
I’ve already taken part in a couple of swaps so far and have received my first rating—whee! Seems fun, and a bit addictive :)