Probably the #1 reason that I’ve been using Firefox instead of Safari has been the lack of “type ahead find” aka “find as you type” aka “that thing where you start typing and it searches the page without having to pop up a window, so it’s like really convenient and you can just press enter to follow a link so it’s good for navigation too”. Acid Search brings that feature to Safari and adds the ability to really expand Safari’s search box. It’s worth noting that Saft, the uber-Safari plugin, adds type ahead find as well.
Another Safari tip that I just learned that will make life so much nicer is that pressing the option/alt key while tabbing through form fields allows you to get to every control, including buttons and combo boxes. It’s always been really annoying to have to reach for the mouse when I hit the “State” field on a form.