For my sins , I am making some prototype displays that use 840 LEDs each.
Because of availablilty here, I am using SAA 1064 chips that can drive 16 LEDs at a time latched, or 32 at 50% multiplexed.
For the proto I am wiring by hand :-( but later ones will have a pcb.
Its I2C driven and has 4 addresses, so you can have 128 LEDs driven by 4 chips from 2 pins of the Arduino .
I am using 7x5 matrix displays, but you can change any LEDs as you wish.
Heres a shot of whats been keeping me busy this holiday season .
This is for one of the chips ( which havnt arrived yet, hence the socket )