While conducting some research, I came across a brilliant website on the specific subject of conversion rates. Conversion Chronicles details a remarkable amount and depth of information on the subject of e-commerce conversion rates, and even has a specific, updated page on the topic of an average conversion rate across the web.

Supposedly, the magic number is 2.3 as an average for all industry segments, but this goes considerably up and down depending on the vertical. Electronics, for example has an average of only 1.1%, while catalog e-tailers average a whopping 6.1% (my guess is that this is due to the traffic that gets driven to the site from the catalog with the specific intention of making a purchase).

If your site isn't achieving these rates, there are two places to look - on the site itself, including design, usability, layout, navigation, pricing, stock, etc. and at the traffic sources. The best website in the world won't convert visitors if they're targeting the wrong keywords.