Traffic Exchanges

Broke people trying to advertise invariably turn to traffic exchanges. This blog is in the process of reviewing a bunch of different ones. Traffic exchanges are a real pain in the ass. You want to find a few that give you a lot of return for the time you end up spending surfing, and maybe a couple that you'll consider upgrading with so you don't have to surf as much. The aforementioned blog may be able to save you some time. It's pretty new but I think will grow into a good resource.
So far this is my favorite traffic exchange. My experience has been very positive and I'm actually going to upgrade.