First of all I'll say that this is by far the best site I've seen and been on for being user friendly. It's easy to navigate and keep up with what's been going on, and by far the friendliest

But i just had a thought (although I'm sure you've looked in to it before now) on something you may be able to try.
What about attracting a couple of sponsors who could advertise on the site? It would help pay for your costs as I understand it isn't free to keep the site going, and it might also fund a little prize or something for say, a quarter yearly competition or something? Although, the sponsors would need to be some sort of web based company to get the most out of advertising on a site where the members come from different countries.
As I said, just a thought.
