Digital Point forum uses a bidding system for their ad space. The advertisers are usually the forum members who want to bring more attention to an affiliate product or site. This ad bid sysetm seems to be very effective, considering they rarely use Adsense now. Is this an idea you would consider using for your forum or blog, where you allow advertisers to bid on ad space, rather than offering a one price solution for ads? If so, what system would you use to capture bids or allow bids? And, which spaces on your site would be open for bidding?