I just installed the 1.1 beta version and it rocks, though I must say I've never really been a firefox fan and always kept using the Mozilla until Seamonkey came out and replaced it.
Now when you hover the tabs in your browser window you thumbnails of the page, really neat
Seamonkey is the continuation of the Mozilla suite.
The development of Mozilla stopped at version 1.8 I think, that's where Seamonkey picked up and they're now at 1.1 beta.
I've used 0.9b and maybe 1.0b, but haven't had a chance to hook up the new one yet. There's a lot of things I like about Firefox, but I still know more about whipping straight Mozilla into shape. Occasionally I will run into a problem in Firefox that I can't sort out, but I can always get it solved in Mozilla/SeaMonkey. So I keep it around.