For a long time, I've used the Firefox option "Search for text when I start typing" to avoid having to type Ctrl-F / Command-F every time to find something on a page. But with more interactive Web 2.0-style pages perhaps using keyboard controls, now I've turned that option off.
However, you don't have to do Ctrl-F / Command-F to activate Firefox's find-in-page dialog. The / key also activates it; that's an easy mnemonic for me, because it is the same key that kicks off search mode in the vi editor. It's the best of all possible worlds -- using alpha keys as shortcuts in web apps, easy access to the Find dialog, and no carpal tunnel syndrome from multi-key "Find" shortcuts.