I've been using Solo Ad Advertising for about half a year now... It was the most responsive advertising I EVER used in terms of RESULTS and, by this, I mean signups and SALES not just clicks on my solos... I used Solo Ad Advertising to promote other ad exchanges and, once, for example, I had a referral upgrade ratio of more than 12%, much better than the general upgrade ratio of that ad exchange... Using Solo Ad Advertising to promote other Ad Exchanges helped me A LOT to earn hundreds of dollars from my referral upgrades and purchases and also from scoring on the top 3 of some referral contests.
Solo ads are an effective manner of email advertising. They’re delivered to a specific audience of double opt-in subscribers who have given their express permission to be emailed offers that they’re interested in. These emails include one stand-alone advertisement which results in a higher chance of them being read and clicked on to visit the advertised web site.