Auction Ads is a program in which I find myself totally surprised.
I don't really have any luck with affiliate ads regardless of how many you see scattered through his blog. I sign up mostly to see how these things work more than 'monetizing' my blog as it's become known.
I started bringing in revenue on the first day! In fact, most days I earn something, even if it's a few cents.
It's pretty simple actually, as are most of these programs.
Install a wee bit of code onto your blog's sidebar to show items up for auction (you can choose how big and how many ads).
When someone clicks and bids on eBay after clicking thru from your site, you earn a percentage/commission.
It's not huge money but every little bit adds up!