Eddy Elfenbein tweeted this fun fact:
Take whatever today's $VIX is. Divide it by 3.46. That's the market's view of the 1 stand dev range +/- for the next 30 days. $$
For those keeping track at home, 3.46 = 12^(1/2)
And here are the results... blue is the +/- expected range based on the VIX and the red is how well the S&P 500 performed over the following month (i.e. one month returns, one month forward).