Affiliate Marketing Manual
To get it you have to join Ken Evoy's affiliate program. You'll find step-by-step instructions showing how you can boost your income from affiliate programs.

Keyword Density Analyzer

Search Engine Watch
Authoritative guide to how search engines work.

Web Commerce Today
Excellent newsletter providing plenty of up-to-date information about e-commerce.

Webmasters.Linkworld.ws
Guide to affiliate programs.

WordTracker
Program tells you how often people search for keywords and how many competing sites use those keywords.