Shaz.am Traffic Network
Shaz.am is a free, ladder-based traffic networking system that helps participants generate relevant, qualified traffic while offering readers links to sites with similar interests. Category-matched links from blogs positioned higher in the network are displayed on your site; in return, your link is displayed on blogs below you (i.e. your traffic network). Links are positioned according to their level of activity - so the higher you get in the network, the more traffic you receive!
Example:
