And this: http://learn.adafruit.com/piccolo/overview
- if you
rework the LED array driver then the FFT part could be useful.
For this sort of music visualization FFTs and DCTs aren't great as they
split the spectrum up linearly - you really want to pick out each note or
octave which takes something a bit more sophisticated (probably beyond
an Arduino alone, laptop or RaspPi needed perhaps).
An Arduino could easily drive LED strips via an array of MOSFETs or Darlingtons,
and could for instance be controlled in real time via USB-serial connection.
Simple FFT or DCT can be done on the Uno / Mega, but don't expect 1024 point
resultion or a bandwidth beyond 5kHz...
The Due is more capable and can handle full range audio at 12 bit resolution,
and has a lot more pins for controlling LED channels, but is 3.3V and would
need careful interfacing (voltage too low for most MOSFETs, current low too, but
enough for Darlingtons)