Famous predictor Nate Silver explains why correlation doesn't necessarily imply causation.
Reasons for Correlations
HSBC Risk Index up to 2011 and Heat Maps showing correlations.
Correlations can imply much greater risk than traders realise.
Bruce Kovner - Macro Trading is like playing Chess
Aussie - Gold a great delayed correlation trade from 12 to 600 hours apart!
John Murphy Video on Intermarket Analysis
Correlations can Help Risk Management!
Surely USDJPY is not correlated to Turkish Lira with a 6 months delay?!