Surprised the article didn't mention zferral or extole (or more recently - spreadable from the chargify guys). Actually quora does a better job: http://www.qu

Surprised the article didn't mention zferral or extole (or more recently - spreadable from the chargify guys). Actually quora does a better job: http://www.quora.com/Marketing/What-third-party-services-can-I-use-to-set-up-and-manage-programs-to-incentivize-my-customers-to-tweet-or-share-information-about-my-company-on-Facebook http://www.quora.com/Marketing/What-third-party-services-can...