Ad server plugin for a small site?

Advert test
Any recommendations for an ad serving plug-in for a small site?

I wanted to add an ad server plugin to one of my sites, so that I could sell advertising directly to a small number of local Irish ecommerce businesses. The site has 100k+ page impressions per month and I was looking for a simple plug-in which would give me enough data to show the advertisers that their ads were being displayed, clickthrough rates etc. I do want to sell the ads ads myself rather than sign up to an ad serving network.