Look what I found! This may be old news to many of you, but this site (and I'm sure plenty of others) lists music by beats per minute! Check it out here. The ideal distance running cadence is 85-95 (correct me if I'm wrong).
Running cadence is how many times one foot (right or left) hits the ground in a minute. I guess we should all be striving for 85-95, right?
That said, if you like to run to music, getting 85-95 bpm music or 170-190 bpm music would carry you right at that cadence.
So halfway through your next run, take a minute to count your cadence. If it's too slow, try shorter, faster steps. And go find some music that can get you closer to the ideal running cadence! Sounds fun to me!