Stumbled across this after the 2008 wreck, and have had an eye on it since. (It works before 1980 if the chart would go that far.) Just follow the MACD crosses to your favorite crash and where we've been for the last year or so.
This is the only reliable major trend clue. Judge for yourself. Until MACD crosses down significantly on the monthly chart (instead of grinding along being rescued by FOMC actions) the rally is still on.