I started with them just a couple months ago because I was interested in the " spikes " they offered to bloggers.
A spike is a low cost boost of viewers for just a few cents that you can get with a couple clicks.
Earning money for the spikes is easy too, because you can click on other spikes, and earn money to promote your own site. I have found it a great way to get in some drops for my Entrecard and Adgitize also.
If you don't already have it, click the link and check it out, its really easy traffic