I like the idea, but I'm not a fan of the website design. I'm not a web designer or anything so take my advice with a grain of salt, but the concentric circles and red makes the site feel really in your face. I'm using google chrome and the ad shows up as a blank brownish box.

While I like the idea, I probably wouldn't use the service on my blog because if no one buys ads on my blog I'm just advertising your service. Maybe let advertisers choose categories and if you have a blog about that topic you can present it to the advertiser?