I have a website that gets around 4k regular uniques per day. It is a one-page website and has no ads. I'm allowing website owners to sponsor it for a day/month for a fee to enable me to work on the website (server costs/promotion etc). The audience is mainly Firefox users (64%), that should tell you abit about what their into; web 2.0, gadgets, social networking websites etc. Please PM me for the URL and Let me know if your willing to sponsor it. I'll be writing a blog post about your sponsor and also giving you a link at the bottom of the page (12k views, 4k uniques). The link won't be search engine friendly, it will mainly be for advertising and exposure reasons. Ask here if you have any questions -- cheers. EDIT: When you send a PM, please put in the subject "SPONSOR", this way I don't get mixed up with other PMs.
I've had a few people requesting information. I would like to say that I don't know how much clicks you would get. There isn't no other externals links on the page so you'll probably get around 20% -- I'm not sure on that.