Michael and guyzzz,
I think I saw another possibility, seems to work well on 10-15 min time frames on ES. Some people explore bullish/bearish centerline crossovers (@ 0.0). Again just an observation over 24 hour prices with MACD suggests that whenever MACD is within 0.1 range to centerline and is either performing a crossover or has done that already (that is important) some time ago, looks very tradable to me. I repeat that is on 10-15 minute chart of ES and range is about 0.1 to centerline.
Romik
EDIT: MACD and signal are based on (O+H+L+C)/4