Here are some great lessons in ecommerce. The first few slides are interesting background, the ten lessons starts on slide 10. Based on our experience this is a great summary.

Pay special attention to lesson #7...

This is a very nice summary by Ben Hunt regarding the current state of web design. He covers the key elements of recent good designs including things like: layout, orientation, scrolling, white space, etc.

http://www.webdesignfromscratch.com/current-style.cfm