In our upcoming book Implementing Automated Software Testing Addison Wesley, publication approx. Feb 2009 (thanks to JakeBrake, Joe Strazzere, and Jim Hazen for their excellent feedback/input so far), I am listing a few testing tool websites - can you think of others:
For Open Source Testing tools, see http://opensourcetesting.com/
For various Web Testing Tools, see http://www.softwareqatest.com/qatweb1.html#FUNC, this site includes popular web testing tools, such as Watir and Selenium
For a sample of Agile Testing tools, see http://functionaltestingtools.pbwiki.com/FrontPage
For a discussion of various popular software testing tools, see http://www.qaforums.com
Any major websites I am missing?