taptempo.py

#!/usr/bin/env python
import time, getpass

class FakeStream(object):
    def write(self, *args, **kwargs):
        pass
    def flush(self, *args, **kwargs):
        pass

print '''TapTempo
 Enter   - count a beat
 q Enter - quit
'''

count = 0.0
total = 0.0
last = 0.0
while True:
    if 'q' in getpass.getpass('', FakeStream()):
        break
    now = time.time()
    if bool(last):
        current = 60.0 / (now - last)
        count += 1
        total += current
        print '\b' * 30,
        print '%7.2f bpm  %7.2f avg bpm' % (current, total / count),
    last = now