Simply divide the end time by the number of taps (don't forget to add any that didn't register) and you have seconds-per-beat (divide 1 by spb, multiply result by 60 and you have bpm), which obviously becomes more exact the longer you tap. If you're really hard core, open the results in a spreadsheet to see your lows and highs.
Just for kicks I did Orbital's "Satan" and tapped 344 times in 187.68 seconds which gives a bpm of 110.09 and seconds per beat of .545. My lows were .42, .46 and 4-.47s, highs .64, .63 and 3-.62s, and I had 42 hits that were .54 (12%). My average for just the first 8 taps came to .544.
(Do I have too much time on my hands?
