you looking to trade traffic or hardlinks? Like if your concern is just that you give away one click and get one click that'll be a different solution than if you're trying to get hard links (
www.yoursite.com without tracking variables) that are good for SE Ranking. If you're looking for hard link trades scope out
http://linkex.dk/. Pretty easy install, no db required, and automated sign up for people who want to trade. Kewl that you can set a PR limit. Like you'll only trade with people who have a PR of X or higher.