Email lists are undervalued. You can get some unbelievable % responses in the Retail business. I would think a startup company that you can create a web blog from an email would be the perfect candidate for this type of marketing.
If you are interested in this space email me chris at thestartupdigest.com
I may be perhaps missing a finer point on why conversion is better.
I sent a note to Posterous support, and they said that Posterous was not meant for email newsletter archives and I should not use it for that reason.
Weird but for some reason it doesn't quite work and they seem to not be focusing on that.