Finding Competitive Intelligence

Want to know which sites your visitors are also visiting?
http://www.alexa.com

Who is linking to your competitor's site, but not to yours?
http://www.linktree.info/

What is the overall visibility measure for your site?
http://www.marketleap.com/publinkpop/

Want all the gory details on a URL?
http://www.faganfinder.com/urlinfo/