Information Architecture: A critical part of SEO01 Apr 2009
One of the most overlooked facets of many major sites is the actual organizational hierarchy. Too many designers and programmers just segment things into a few quick sections without doing any deep thinking on the issue, which can lead to major issues later.
In that vein, Audette Media has an excellent tutorial on the basics of Information Architecture for SEO. If your digital inventory of content and media isn't well organized, it won't just be hard to find for humans (leading to a higher bounce rate), it will also be shorted by search engines, leading to a loss of precious search engine position.