General Links
PlanetChristmas.com - The ultimate website about anything Christmas.
LightORama.com - The creators of Light O Rama.  The vendor of software/hardware to sequence lights.

Other Notable Christmas Displays
LightsOnDisplay.com - Mike Z's house lit up with amazing video sequencing in Sherman Oaks, California.
Lindsaylights.com - A very lit up house in Canada.
Holdman.com - A great display in Utah that has a live webcam.
ProjectXmas.com - Chase's display in Reno, NV.  A fantastic display using wireless to control neighbors lights.