AD Exchange

Ad Exchange Sites are sites where you can view ads submitted by other members obtaining credits and post your text or html ads using your credits, all directly on the site, without receiving tons of emails to your mailbox.
They offer different Tools, like Solo Ads, Traffic Links, Banner view, List Building, Url Cloacking, Referral Earnings and more.
Sometimes there is a PTC Ads section (AdzQuik, Vital Advertising, Traffic Zoom and others), with the ability to earn up to 0.06 $ per click
To me these sites are one of the most effective tools to promote your Business.