safari has tabbed browsing.
there’s some extensions for mozilla, and if you like making your shit look different, you can get some solid themes for it. the only extension that was pretty sweet that sticks out in my mind was the mouse gestures. i’m not sure that would even be that great on an apple. i guess it would depend on what your setup is…laptop or desktop.
wasn’t there a program called camino for apple by mozilla? supposedly it was firefox, but for mac, and it ran a lot better than firefox did. i never tried it though so i don’t know.