I covered in a previous post that listing my blog posts in StumbleUpon produced a massive spike in my web traffic.
Now I didn’t realise until this morning that StumbleUpon actually sells traffic. You can purchase stumbles at $0.05 (£0.024) per click. In terms of qualification you get to choose the category you want traffic from, the location, sex and age. You can also set a daily budget
The traffic will be pretty untargeted and so is cheap. I would recommend that businesses try it out and see what conversion rate they get.