Incremental search is one great feature in the Firefox 1.x series. Press /, or simply start typing, and Firefox searches as you type. Firefox 2.0 has the same feature, except it is missing the “Find Next” and “Find Previous” buttons. Here are three ways you can get this functionality back:

1. Press F3 to find next, and Shift-F3 to find previous
2. Start your search by pressing Control-F (Command-F on OS X).
3. Muck around with your Firefox configuration to turn on the buttons

Mozilla call this feature Find As You Type. Follow that link and you’ll find a few more usage tips.