As far as moving averages are concerned, I find them extremely useful for seeing vulnerabilities in the market. Not specifically the 200 day, but all of them, with price taken away, is very informative to me.
Nice idea treeman. I'd wondered before about displaying MA's without price and your post inspired me to find a way to do it (I simply changed the chart style to close line and re-set the line colour to white, my background). The MA's really jump out of the screen now.