Found a neat little chart that measures the amount of 'fear' words in common media and it's relationship to the Nasdaq. As one would guess, it's better to buy when there's fear than fearlessness.

The MarketPsych Fear Index shows a 10-day exponential moving average of the percentage of "Fear" words in the U.S. financial news displayed over a candlestick chart of the Nasdaq 100 (QQQQ).
http://www.marketpsych.com/mkt_analysis.php