We've been experimenting with some low-cost methods of driving traffic to our site. We've found that the site has quite a bit of appeal to a general audience. One of the sources we've found that has been great is paid StumbleUpon ads. We can do a fair amount of targeting and get traffic at $0.05/click. As you would expect the traffic isn't super high-quality but given the low cost/click we've been pretty happy. I'd love to hear what other good low-cost traffic sources might be out there. Ideally we'd like to drive traffic at a price lower than $0.05/click and are searching for other opportunities to do this. Any suggestions?