iPhone & iPod Touch’s instant access button (you can allocate functions)

I’ve found it quite hard to quickly turn up and down the volume of my iPod Touch when I want to on a crowded train. There is lot of noise when the train is running, so I turn up the volume, but when it stops, it becomes quiet around so I have to quickly turn it down. When I was using my old iPod shuffle, it was quite easy to manipulate the basic functions even when I wasn’t looking at it. So naturally I want that usability for my iPod Touch.

You know there’s a button on top of iPhone and iPod Touch to lock/unlock the screen. I think that can be used for a few useful purposes. As iPhone and iPod Touch know which side is now up and which side is down, it should also know “when the button is pushed with this side up”. So there can be a few functions you can customize like:

If the button is clicked when…
1) the top side up — lock/unlock the screen
2) the bottom side up — mute/regain volume

And if the button is clicked TWICE when…
3) the top side up — access the homepage with Safari
4) the bottom side up — YouTube launches

Something like that.
What do you think?

Examples of the button usage
iPhone & iPod Touch’s instant access button