Selling/Buying Ads on your site...

Just looking around to see if this might be a decent way to add income. Here are some sites where you can either buy an ad placement on someone else's site, or sell some space of your own...

adbrite

I have not tried this fellow before:

Performancingads.com

Also, Jim Kukral had a nice piece a couple years ago, just to help you get organized on your blog:

Jim Kukral