Choosy - Choosy opens links in different browsers as specified, according to rules, set by the user.
CrossBrowserTesting - Browser Testing made simple! Run automated, visual, and manual tests on 1500+ real browsers and mobile devices. Test more browsers, in less time.
Account Surfer - Quickly switch between accounts and browsers on Windows
browserling - Live interactive cross-browser testing from your browser.
Finicky - A MacOS app for creating rules that decide which browser is opened for every link that would open...
Browsershots - Browsershots makes screenshots of your web design in different browsers.