Just reviving the talk we had in the old forum. How about using the Arduino to get some nice SID, Synth, Analog, sampled, etc ... sounds.
Here's a great project using the ATmega88, not Arduino based, but still, check this out.http://www.linusakesson.net/chipophone/index.php
"The synthesizer is implemented on an ATmega88, an 8-bit microcontroller with 1 kB of RAM and 8.5 kB of ROM. It receives MIDI data at a jumper-configurable baud rate and produces a 12-bit mono line out signal. What follows is a brief architectural overview."
It has 8 voices!!!
I will post some other links and ideas soon.
Best Regards, WilliamK