As much as OS X
As much as OS X and macs are generally easy to use, there are a few major features that are well-hidden. I'm usually a fan of hidden information spaces when they are supplimental or simply serve as shortcuts, but booting into another OS is a fairly big deal that shouldn't be obscured.
I boot into OS 9 once in a blue moon, so seldom that I forget the secret keystroke to access my OS 9 partition. It seems silly that I have to look it up every time, why can't I choose "restart into the alternate partition" from the main apple drop down?