Agreed, projecting on the visor like a fighter pilot helmet would be the best IMO. That way you can flip it up and it's not in your face if you want. Plus the visor is bigger and a better distance from your eyes than a google-glass-like window. You also would have more real estate for projecting information and telemetry data. And both eyes could then see it instead of just one.
I'm still waiting for this feature in cars for the windshield. Heck, my 1997 Pontiac had a cheap HUD that displays the speed and radio stations on the front window, why aren't we putting GPS nav and other information projected onto the front window by now. It's freaking 17 years later (from when my car was built) and there are STILL only a handful of cars doing this today, most common being the Corvette. Even the ones doing it today are still only putting a couple pieces of info on the window, same as my car did 17 years ago (speed, radio, and maybe what gear your in?). With tech being cheap today, I want this as an option on normal everyday cars as well (obviously as an option, so your not forced to buying it).
How cool would it be to have a HUD version of GPS of where you need to go overlaid on top of what you are seeing, or have some augmented reality street signs projected as you drive around an unfamiliar city. Add in your speed and a couple other car operating status displays, maybe a rear or side camera views to help with lane changes, and you got some useful information that you don't have to take your eyes off the road for. You could even do a night vision/FLIR front cam projection, so at night, you can see better (like Cadillac did years ago), except projected in front of you.
This would have to be way more safe to have this information transparently floating in front of you that needing to look down at a dash mounted GPS, or at your cluster, or at your radio when changing channels etc.
Something like this: http://www.google.com/url?sa=i...