browserling - Live interactive cross-browser testing from your browser.
BrokenLinkCheck - Free Broken Link Checker / Online Dead Link Checking Tool - find bad hyperlinks
Browsershots - Browsershots makes screenshots of your web design in different browsers.
Dead Link Checker - Check for broken links on any website
BrowserStack - BrowserStack is a software testing platform for developers to comprehensively test websites and mobile applications for quality.
LinkChecker - LinkChecker is a free, GPL licensed website validator.