Wired has got very cool compilation of LED-lighted buildings (compiled from LedsMagazine).
This one is the Agbar Tower:
This Barcelona office, designed by the French architect Jean Nouvel, brings color 142 meters into city skyline. A total of 4,500 L3 RGB lights were installed to illuminate the 32 floors of offices in the Agbar tower. The lighting system, which contains 4,500 L3 RGB lights, is controlled from a single computer.