That actually sounds like a cool idea for a new wave of mobile apps...
Anyone remember the "emotion wheel" from that Microsoft Comic Chat [1] app of old? If I recall correctly, when you typed something like "lol" it would automatically pick the laughing image, and so on.
Something like that, with reconstructions of your actual face based on how your voice sounds (after you've trained it with a few expressions) should be possible with current tech.
Google Hangouts has a feature that sounds a bit like Comic Chat. When you type in certain phrases an animation will briefly play at the bottom of the window. Certain triggers I've noticed are "merry christmas", "happy birthday", "happy new year", and "lolol".
