firefox 3's location bar is a mess, not just because of this issue. It will suggest me a gmail authentication string for almost all of my inputs. There are lots of ways to do this better. I like chromes way of doing it, but it has some privacy issues.
If you select a different entry then that entry gets promoted next time you type the same string. So if you type "g" and a gmail address comes up but you cursor down to "engadget" (say) then next time you press "g" engadget is more likely to come up. After a few iterations g will bring up engadget as the first selection. It's awesome!
