My selection of the many available resources:

Demographics, Marketing News & Techniques

• eMarketer's eNews
• Clickz Today

Site Navigation & Usability Assessment

• Coremetrics

Marketing Strategy

• Marketing Experiments
• Marketing Sherpa

Search Engine Optimization

• Bloofusion

Search Engine Promotion

• Search Engine Watch
• Planet Ocean - Search Engine News

Directory / Content Promotion

• About.com
  (do a keyword search to find appropriate sections, then write a brief, non-commercial pitch to the section editor)
• Article Submission Sites

Local Promotion

• Yahoo! Get Local (click on your state and city)

Yellow Pages

• BigBook

Traffic Analysis

• Omniture

E-mail Marketing

• Topica Mailing List Directory
• PostMaster Network (for purchasing opt-in e-mail lists)

Press Release Resouces

• PR Web
• ProfNet

Media Directories

• MediaFinder

And, don't forget my free tipsheet containing 23 different ways to promote your site "Beyond the Search Engines".