Jay, you brought in a crucial concept: spacing out everyone's requests over time.
That is key, so that everyone gets some chances to request the popular things, not just those who can poise over their keyboards during the opening minutes or hours.
That can be done many ways, like "five Oinks per day max" or "no more than N oinks per day from each trader".
After a few years I noticed that some savvy traders deliberately held back some seeds until after the initial rush was over. They would add seeds during the whole duration of the swap, so that (bad thing) you had to keep re-checking their lists, and (good thing) there was often something fresh to look for or search for even if you missed the first frantic day of trading.
Almost any scheme that stretches it out, could help.
Hmm ... would there be value in showing a public list of seed types that had run out? If I knew that every one of 20 offered packages of radishes had been snapped up, I would think "RADISHES?? Who wants RADISHES?!?" and then offer all those pkts that have been sitting in my stash since the last time I went crazy with a seed catalog.
