Browser browser, which one to add

I love Firefox, it does everything I need from a brower with the add-ons I've installed, however how I work, I need to run two copies. I use Google Doc's, and a few other sites that you can only be logged into with one user name per browser. I had tried using a bit of coding to run 2 separate instances of Firefox, however I ran into a few issues so needed to use a completely different browser. Which one to use. I tried Safri, IE, Opera, and Lunascape. Didn't really like any of them then I found Flock.

Flock is basically Firefox for the social web animal. I'm not using any of the fancy stuff, but it runs like Firefox, and can use the same add-ons, so I can run two browser windows with Google Doc each with their own user. So if you need to be signed into a site under two different user names, and love Firefox, may I suggest Flock.