Unfortunately, conversion rate is probably one of the most dangerous and mis-used metrics available to site designers to measure how good their site is. They apply it as if it is telling them something and, worse, when they optimize for it, they can create a site that looks like crap and produces undesirable customers. — Jared Spool
Jared Spool’s five part series on moving beyond conversion rates is an excellent read for anyone being blindly tasked with increasing conversion rates on a site: