Blog Traffic Exchange (http://www.blogtrafficexchange.com) just launched their service via a wordpress plugin… http://www.blogtrafficexchange.com/related-websites/ or http://wordpress.org/extend/plugins/related-sites/ The Blog Traffic Exchange is an Amazon 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. How does it work? After installing the plugin you will receive related posts from member sites that will be displayed posts at the end of your posts. Links are randomly rotated both locally per page load and globally every 24 hours. A proprietary traffic balancing algorithm rewards blogs that send diverse traffic into the exchange more frequent placement. Relevancy is never compromised. (To see it in action here are 2 blog posts on the BTE blog which demonstrate related websites: Music Blogging and Page Rank 5 in 1 Month).
If you want to read some uncolicited opinions from my beta bloggers... http://forums.moneyblognetwork.com/viewtopic.php?t=3772
Unsolicated review that says it all: http://www.jackhumphrey.com/fridaytrafficreport/new-link-building-plugin-for-bloggers/