As part of my effort to spread Firefox, I'll mention that Firefox 1.0 Preview Release was released last week.
Some of the features that are either new, or I haven't noticed before: Find As You Type now has it's own toolbar, secure sites have better indicators at the top of the screen, RSS live bookmarks, default mail program integration, and more.
Most important, if you're using a version of Firefox prior to 1.0, you need to upgrade to fix a number of security holes.