The Temporary Containers was a nice add-on built on top of that.[0] While it's a pain in the aspect of cookie-use across domains (like logging into Azure), it's other features out-weigh the initial nuissance - like automatic deletion of the container, as soon as the last one for that particular domain is closed. All of this is, of course, configurable.

This wasn't meant to be a plug, just a happenstance of "if you like 'x', have you seen 'y' based on it?". =]

[0] - https://addons.mozilla.org/en-US/firefox/addon/temporary-con...