the big 3 on the "dark side" are Camino(mozilla w/ a Cocoa wrapper), Omniweb (oh my god, the UI is heavenly! but no tabs
) and Safari. if you work in them, you've covered probably about 3/4 of your Mac audience. sadly IE does still have some following, but i forecast that dying down a LOT as IE becomes an optional install in Panther, and Safari keeps improving. it's not a bad little browser, although I'm a camino fan myself...