DVDdoug:
If you're out of I/O pins, the only thing I can think of is to get rid of the LED matrix and use [u]shift registers[/u].
I think what was meant was.
Keep the matrix, BUT drive it with a shift register.
OR
MAX7219 IC.
Google Arduino 8x8 MAX7219
It will give you examples, modifying to 5 x 6 should not be hard.
Tom... 