I feel I should go into more detail. My wife and I share a laptop and browse email. Currently we keep coming back to each others gmail accounts, having to log out and log back in. Are there any good extensions or addons that would allow us to toggle back and forth between these? This does not necessarily need to apply to just gmail but include any cookie, session, etc. I'd be willing to use Firefox if such an extension exists on it as well.

Much appreciated!