beamer: How to add a new option for the frame environment

In some frame I want the title rotated at the left side of the frame. This happens more frequent in 16×9 formats.

How can I redefine the frame environment to add an option, that allows me to do that.
If this new option is not used, the original frame behavior is applied.

Something like this:

documentclass{beamer}
begin{document}

begin{frame}[rotatetitle]
  frametitle{My Rotated Title}
end{frame}
end{document}

It could also be an option to the frametitle{} command.

While I could solve this particular issue with a new variant of the frametitle command (which I am doing now), I have several optinal frame behaviors in mind, that I would like to switch on and off with options. Examples are: make the textwidth wider and suppress the foot line. So I am looking for a general mechanism to add options and optional behavior to the frame environment, while still keeping all the default behavior and existing options such as fragile.
What would such a mechanism be?

–Axel