If you use Qubes like I do, you have many different AppVMs to compartmentalize different programs. You might have one VM for your email client, one for your jabber client, one for your password database. But if you click a link in any of these programs, it sure would be nice if that link opened in the browser VM of your choice. This isn’t all that hard to setup.
qvm-open-in-vm lets you open a document or a URL in another VM.
user@dev:~$ qvm-open-in-vm Usage: /usr/bin/qvm-open-in-vm vmname filename