Entrecard recently launched a new feature on the site: Entrecard Market . In the market you can use Entrecard credits to buy services, advertisements, and even real items from other Entrecard users- and sell your own products and services.
I have already listed two adspots (look in the corner there at the top) on Entrecard, I am charging 3000 EC credits for a 1 month ad, you can purchase that here.
I am also selling links in my blogroll here for 1 week at a time for 500EC here.
Don’t know what Entrecard is? Check out their new promo video for a fairly detailed overview: