Dead-links.com - Free online link checker. Spider-based technology and fast online analysis. - http://www.dead-links.com/
NetMechanic - Tune your web site with link validation. Robot will find broken links in your web site. - http://www.netmechanic.com/
HostPulse.com - Identify broken links in your site for free.The broken link checker will search your site, testing each link it finds and report the status of each link. - http://www.hostpulse.com/app/networktools/chklinkform.asp
Link Valet - Generates a color-coded report by spidering a site or checking links on a given page. - http://valet.htmlhelp.com/link.html