ExitExchange Free pop-up window exchange that opens one webpage behind each surfer's current window when they exit your site. Receive visitors in exchange for placing the pop-up code on your pages. I like button exchanges more because they take up a fraction of the space and loading time. 88x31 pixel or other sizes, stats, and extra traffic for referrals. ButtonXchange Another good 88x31 button exchange program.
Free button templates to use, stats, a top site list, and a top click through button page.
TextSwap Place a simple text link on your site and get 1 guarenteed hit per 2 hits from you. Text links have a much higher success rate than banners. Also get extra hits for referring new members. The concept of this site is that someone visits your site in exchange for you visiting their website. Your banner is placed on the member page of each member whos site you visit.