SEOMOZ
An SEO company with an excellent reputation, SEOMOZ is also full of articles and resources on SEO.
Search Engine Roundtable
A rather unusual site with a mix of forums, articles and links to current SEO threads online.
Blogs
Since SEO is constantly evolving, I've found that one of the best ways to keep on top of current trends is to read the blogs of SEO experts, and learn which theories are currently being debated.
Jim Boykin's Blog
Jim Boykin of We Build Pages writes on SEO with an honest, inquisitive and often humorous style.
Matt Cutts' Blog
Google employee and spam fighter, some quite interesting posts but perhaps not as open as you may hope. Read between the lines.
Matt Cutts' Blog
Google employee and spam fighter, some quite interesting posts but perhaps not as open as you may hope. Read between the lines.
Greg Boser's Blog
AKA Web Guerrilla, a Search Engine Marketer with loads of experience, who also hosts SEO Rockstars on Webmaster Radio.
Todd Malicoat's Blog
One of the most interesting and unapologetic SEO blogs I've read, always provocative, and always stimulating.