Here is a plot of the total put/call ratio. Readings of over 1.25 as occurred today are typically very near good buying points. Also when the 4 day moving average hits 1.1 it has shown a real extreme that marks a buying opportunity and today's reading was 1.21.
[j6534876,y]&r=6870>
Really surprising how extreme the sentiment indicators are given the market really hasn't declined that much.