What about multiple "users" in Chrome? If you go to the settings page, you can add additional "users" and then open a window as another "user" using the icon in the upper right corner.

Each user gets their own profile: cache, cookies, history, saved data, extensions, etc. The only thing shared should be IP address and user agent. (Unless the user infects the profile with a url that identifies them.)

I use this for testing, isolating my facebook profile, and isolating all of my banking sessions from my main browsing window. (Just in case they have a CSRF issue.)