White List URL Browser Selector?

malcomvetter asks: "OK, so I'm stuck working in a Microsoft environment. My preference is Firefox for the external 'untrusted' web content out there and our internal 'trusted' web apps require IE, but rather than pick one browser over the other as 'default' I came up with this idea: I want a tool that gets installed as my default browser in Windows, and all URL strings that Windows passes to it can then be simply regex'ed for domain and then routed (re-passed) appropriately. Hence, having the ability to allow admins to maintain a white-list of 'trusted' IE sites (or [insert browser here] sites) and those URLs are passed to IE, all others defaulting to (in my preference) Firefox. And when I thought about it, I was surprised that I hadn't heard of an existing tool to do that. I have used the Firfox extension for 'open in IE', but I'd like a tool that I can configure and forget about. Has anyone seen such an app? Would it be an extremely hard thing to build?"