Really I just wanted to post something and keyboard shortcuts are as random as any other reason. For some reason a lot of shortcuts aren’t widely known. There are two shortcuts I find really helpful when turning on my computer at school. If class has started or something and you can’t remember if your computer is muted or not, you can hold down the “mute” key immediately after pressing the power button. This should cause the boot chime to be silenced. I haven’t tried it yet on the new Macbooks, but it worked on my old MacBook Pro and I’ve used it on the Air too.
The second shortcut every good “Genius” knows. Holding down the mouse button, or in some cases the spacebar, will eject an inserted CD at boot. This prevents the annoying “wurring” noise I get when I leave in an old video game or something in the drive before turning it on. However, this does come with the obvious clicking as it ejects.
There is an article for most of the interesting shortcuts available: http://support.apple.com/kb/HT1343