I know a lot of people using Numista try to get coins from as many countries or issuers as possible, myself included. It would be great if the swap lists indicated if the coins a swap partner has on offer are from countries I either already have represented in my collection or are yet to be represented. Maybe some sort of graphic (e.g., a checkmark indicating "I have this country" and an "X" if I don't) next to the country name.
“Do not meddle in the affairs of wizards, for they are subtle and quick to anger.”