Search Engine Optimization / SEO

Important SEO Blogs

SEObook
seomoz
WebmasterWorld
Matt Cutts (Head of Google's webspam team)

Search Engine Optimization Tools

Quantcast Estimate traffic, rank and metrics of a web site
Compete Estimate traffic, rank and metrics of a web site
Alexa Estimate traffic, rank and metrics of a web site

Link Building

Strongest Links Detailed list of directories to submit to
PRWeb Press release distribution
E-releases PRnewswire press release service
WL Marketing Low quality press release service

Misc Sites

Info Please Biggest Cities List