Just as bone indicated, correlations are best used as a screen or first step in looking for something else that offers value in trading. Correlation itself is not a trade setup or edge.
Pairs trading strategy... a strategy not easy to implement ... cos you need to monitor multiple pairs while you also need to monitor multiple timeframes... I used to use this in Forex using cross pairs but I have stopped doing it because this strategy requires high level of concentration and sometimes makes me very aggressive. But I admit this strategy can produce higher profits than any other strategies.
Some more on-the-run inter market correlations based on daily settlements. I blend the results from two different statistical studies, and most importantly, I use the results as a simple SCREENING method to see if a combination warrants further investigation. FDAX vs CAC 40 1 Month 0.887 3 Months 0.968 6 Months 0.904 1 Year 0.900 2 Years 0.941 5 Years 0.970 Copper vs Canadian Dollar 1 Month 0.901 3 Months 0.533 6 Months 0.839 1 Year 0.942 2 Years 0.962 5 Years 0.947 10 Year Swiss Note vs 5 year German Bobl 1 Month 0.943 3 Months 0.697 6 Months -0.085 1 Year -0.075 2 Years 0.805 5 Years 0.859 ICE Gas/Oil vs 4 Year Russian Government Bond 1 Month 0.918 3 Months 0.836 6 Months 0.536 1 Year 0.188 2 Years 0.229 Indian Rupee vs Coriander (NCDEX- Food&Fiber) 1 Month 0.729 3 Months 0.728 6 Months 0.677 1 Year 0.114