There is one called EasyCJ7.0 that is free if you put 5 I think it is of their banners on your webmaster pages. I like it. It doesn't take any traffic, shows proxy hits, uniques, ect. It's fairly easy to use and they install it on your server free.
Here is a sample of the banner you have to display. (No referral links, LOL)
http://www.the-pornstar.com/webmasters.html