Beside of faster ma crossing slower ma, you may want to consider price crossing certain ma for example in one of the short course i attended, there was a suggestion of using 50 ema (in trading environment) to catch the price momentum of the GBPUSD (using 2 hour chart) and get out from the trade using an indicator i.e. stochastic perhaps. the 50 ema is quite significant and price will usually move toward the direction of the crosses (cross above means move up and cross below means price move down).

Just an idea, maybe you can come up with a great trading system .