Quick response within a session

I think it would be really good to have simple kind of response system.

Moderator is asking something and want to know the opinion of the audience. He/She just need to hit the "QuickResponse"button and (all) get the feedback just in time within an little overlay (on the whiteboard?). Hitting the "QR" button again the overlay disappear and session is going on.
I used a kind of reduced wb toolbar (mentioned in the discussion of math support) to prepare the mockups...