Rand Fishkin of SEOmoz has posted what I believe is a very informative article on how important landing page optimization really is to the total effectiveness of a website.

If Google sent SEOmoz 10,000 extra visitors per day, it wouldn’t be nearly as valuable as increasing our current conversion rate by 1/2 of 1 percent.

I believe that the same probably holds true for all websites that have yet to strategically and thoughtfully optimize their landing pages. Of course this process relies on good web analytics and conversion tracking also. Rand also linked to some websites, of which I found Jonathan Mendez’s page to be excellent.