I've just realized I have blogged a lot about Entrecard, but I haven't really written an introduction to it. So here it goes:
If you have a blog, Entrecard can bring you extra traffic. A quick rundown of how it works:
1. You sign up and place their widget on your blog. Since you are new, advertising on your blog costs 2 EC, which is the cheapest. Almost immediately other bloggers (there are already about 8000 of us in the network) flock to you to request for advert; for each new advert request your advert price doubles (i.e. ad price = 2^n where n = number of ad requests; mine for example is 256 EC's right now).
2. For each ad request, you get 1/2 of the price (i.e. if your ad space is worth 512 EC, you get 256 EC). This is so that inflation will not occur in the system. You can also earn credits by going to other blogs with the Entrecard widget (like mine 
) and dropping your card on them (i.e. clicking on their Entrecard widget). You also earn credits when other bloggers go to you and drop their cards on you.
3. You can then use the Entrecard credits to buy advertising on other blogs.
For almost two weeks now I have installed the widget on my blog, and I am receiving an additional 150 visitors on the average. Some of these visitors I came to know personally as friends, and in this manner Entrecard is also good for networking.
Unfortunately, Entrecard only currently supports blogs, although I have seen some which have used it for non-blog websites.
