Icons really are the most expensive thing we can offer, though, so anything revolving around icons/giving more icons/etc has to be really worth it for us to do. Icons are the only thing we can offer that don't benefit from an economy of scale -- most things, the more you have, the cheaper you get per-unit, but with icons it's the opposite; every additional icon we let someone have is more expensive, in terms of site load and cost to us.

With the percentage of $1 payments eaten by transaction fees, the remaining leftover revenue isn't really enough to justify allowing more icon space, I'm afraid. We haven't worked out exactly how much each icon costs to offer -- it's certainly only in the realm of pennies, and this proposition wouldn't lose us money, but it wouldn't be as much of a moneymaker as one might think.