I'm with Joel on this one. Don't install high-bitrate but low-information-value features, keep it simple and clean. People come here for discussion. Install a donation system.

One other idea: the JBL forum had a raffle and raised a substantial amount of money by selling tickets to a nice speaker. If one of the more affluent members were to donate something, the proceeds from a raffle should pay the hosting costs for the next ten years or so.

Btw, why don't you give us the plain numbers - what are the costs of the board, how much would the Google adverts bring etc.? We could then better judge if donations would be sufficient to cover the costs.