How many people heard of Entrecard? I think it is great. It is like having your business on an electronic business card. It is completely free to sign up. You earn credits when people drop their business card while they are on your site and when you drop your card on other sites. Do not worry, when somebody drops their card it does not show up on your site, you see it on your dashboard at Entrecard.com. You use your credits to advertise your business card on other people's website (after they approve it to be on their site) and people can request to have their business card displayed on your website. You approve the ones you would like to display. I have got some good traffic from entrecard, I recommend using them. It might sound a little confusing but check it out, it is really simple and worth it! It basically breaks down to Entrecard is a system of advertising with electronic business cards. Oh yeah and you do not need any kind of referrals to get this free traffic.
Already using Entrecard? Don't forget to "drop yours" when you visit sites.