blogtrafficexchange.com
Features:
"The Blog Traffic Exchange is an cloud based service based on the SEO concepts behind various blog related posts plugins. Using proprietary chaos and relevancy algorithms in conjunction with the Sphinx open source full text index engine, the Blog Traffic Exchange exists to increase your blog traffic by exchanging readers with other members."
Is there an adult version of this? If not, someone should build one. Of course, with anti-cheat/anti-bot features.