Increasing Your Online Conversion Rate

Robbin Steif gives a great summary of how to increase your online conversion rate. It has me thinking about how to measure the impact of aesthetics on conversion. There's art and then there's the art of conversion. How much are clients willing to pay for design - in usability or look-and-feel - that does not increase conversion rates? And where does one look for facts about what kinds of design increase conversion rates most?

When this blog grows up a little, I would like to see the discussion happen here. For now, I'm looking for others up to the task.

Any suggestions?