To test your ASP.NET or AJAX development in Visual Studio with more browsers (Internet Explorer, Firefox, Safari, Opera, ...), right click an .aspx file and choose "Browse with..."
- Add some additional browsers to your "Browse With" list, like FireFox or Safari
- If you want to view the page in multiple browsers, CTRL+click each item
- If you want to open multiple browsers every time, click "Set as Default"
- Hit "Browse" and all of the browsers will open for the specified page
(Via Ron Buckton)