Most web advertising runs on a Cost-Per-Impression (CPM) basis. That is, you pay a pittance for each time the ad is displayed, whether or not anyone clicks on it. Monitoring that seems like too much trouble to me, so I'll offer monthly rates.
- 728p X 90p leaderboard: $30 per month
- 200p X 100p sidebar: $13 per month
- 728p X 90p bottom of page: $9 per month
As for ad content: I'll take .jpgs and tastefully animated .gifs. I can host the file here on Blogspot, or you can on your own site (preferred). The latter has the benefit of allowing you to change the ad content at will. Ads must be relevant to the purpose of this site, and I'll be the final arbiter of what is and is not acceptable. I'll take paypal.
If you have questions, leave a comment with your contact information anywhere on the site. Include a short description of your business and your ad proposal. I won't publish the comment or your contact info. If you don't leave an email address, I can't respond.