I'd go for a donate button (people who donate get an icon). Once we work out what the potential extra benefits to membership might be, we revisit the membership idea. I think a tie-in with GP's printed products would be a great idea also. The cafe-press idea is a good one too, although only if we only have to pay for it if there is an order and there is no periodic flat rate subscription fee that needs to be paid to them even if there are no orders.