Entrecard economy

So. Economy. As suggested, we're going to have to make some changes. There's just too much credit around, slots are filling up fast. It seems that people really quite like dropping cards - we've recorded 2,119 card drops so far, and each one puts 1 credit in the dropper and 1 in the dropped user, resulting in..a lot of credits floating around.

We have in excess of 10,000 hours of advertising loaded currently, and that isn't dropping, with 17 spots currently full.

Some other interesting(?) statistics:

Type	Max/user	Avg/user	Total (all users)
Earned	227	54	5050
Spent	228	24	2286
Holding	199	30	2764

In essence this means that there's a bit too much credit lying around, and not enough to spend it on. Obviously as more and more people join up the amount of space that can be advertised on will continue to increase, so in a sense we're trying to predict a moving target in terms of precisely what the appropriate income vs outgoing is.

We have plans to introduce additional things to spend credit on, but we're also looking at increasing the cost per ad slot with less return. Ie, we could boost the ad spot cost by a factor of 4 (so a starting slot is 4 credits) but the owner of the slot only gets 1 credit for the ad (75% tax rate! :).

We're not certain yet exactly what we're going to do. Feedback welcome, as are requests for additional aggregate data.