here is was i did with mimin.
this is an extract of a much bigger project and give more as a base of study rather than a complete tool.

basically i recoded the whole beatdetect myself. it's based on analysing the spectrum divided in logarithmic bands (12 per octave) As our ears are logarithmic, it would make no sense to use linear bands.

then for each band i compute a score which is based on the volume of the band compared to the band for the last X seconds. this allows me to detect attack. (our ear react to attack rather than volume).

the result of all the bands is then combined back into one global score.
each band can be enabled/disabled to focus on specific regions of the spectrum (works well to catch only the snare for instance)

in parallel i also compute an automatic adjusting parameter that will adapt itself to the "variability" of the music (the beatSense variable) so that we don't catch too many or too few "beats".
the sensivity of this detection can be adusted by altering beatSenseSense. (yeah i know, stupid name that is )

on the graphical user interface you'll see :
from top-left to down-right
-the current score slider (which turn red on beat)
-the current beatSense (the beat threashold if you wish)
-the big red beat indicator
-the sectrum displaying for each band :
  -level
  -average
  -score of the band


i hope this can help someone

http://motscousus.com/stuff/2008-02_Processing.org_patterns/test_beat.pde