When I was playing with with LED matrix, I was bored and frankly tired of staring at RED leds, so I had some BLUE led matrix custom ordered and made a board for it. I have some extras for sale.http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=390568835690&ssPageName=STRK:MESE:IT
Also if you just want the LEDs, you can have them, too. These are compatible with LedControl library -- pins are identical with schematic for LedControl lib.
They are 32mm by 32mm and 3mm diameter.
It actually is much nicer and bluer in real life.