Great post and I couldn't agree more on how important retention is for web businesses. Our product, Nurture (http://www.nurturehq.com http://www.nurturehq.com),

Great post and I couldn't agree more on how important retention is for web businesses. Our product, Nurture (http://www.nurturehq.com http://www.nurturehq.com), addresses this need in a flexible fashion and is being used for exactly this requirement (User Lifecycle Marketing for improving engagement) by a few customers.