I'm organizing a group order for LED drivers ICs from Kingelectronics.com, particularly the Macroblock MBI5168 (but they have other nice things too). As they only ship via UPS this is the only way to get the shipping costs per piece down. This chip is used in the Rainbowduino BTW.
It's basically an 8bit shift register much like the 74HC595, but with included constant current sink drivers (5-120mA per pin). Very nice for LEDs of all kind. And of course for common anode RGB LEDs, which everybody likes 
I'll order on January 14th 2010. More details here.