Thanks for the info, guys. That gives me something to think about. Hopefully I'll be able to join in on the postcard fun soon
Just checked the USPS site, and it says the minimum size for a postcard is 5x3.5, so I could make 4x5 postcards if I just wanted to. 6x4.25 is the biggest size, though, so no 5x7 postcards without paying more postage, but I probably wont ever send out enough at a time for the difference in cost to be a problem.
I'll sit around and think about it for a while. I'm trying to use this as an excuse to get a 4x5 or 5x7 camera. I doubt a few rounds of postcard exchanges is going to be a valid excuse for she who must be obeyed, though