I am currently building and LED clock. I just discovered addressable RGB LEDs!
I think the Chinese have beat me to it again : 64x32 red-green with drivers for $26 http://www.led-card.com/product_info.php?cPath=27&products_id=112
P4.75 Indoor SMD single color LED module
Brightness adjustment: 256 Levels of each color(R,G,B)can be adjusted manually and 8 levels of each color can be adjusted antomatically
Input signal: RF,S-Video,RGB,RGBHV,YUV,YC,COMPOSITION etc.
Control ststem: PCTV mon-linear editting card+DVI display card+main controller card+optic fibre transmiddion
A single order's delivery fee will be 25 USD or 20 Euro, no matter how many goods added in the order.