I will tweet what ever you like to my 9K+ followers on Twitter. We have a VERY active user base so purchasing this gig will get you mass exposure!
This is the official Twitter account for http://www.webmastersrule.com which is a popular webmaster forum so a lot of people are targeted under things like social media, webmasters, web hosting, programming, forums, seo and other things along those lines.
Limitations - What the user will and will not tweet about.
-Anything related to warez
-Gambling
-Pornography or anything illegal.
