Finally caught "Curse of the Golden Flower" over the weekend (which I liked) and kept thinking it was probably the most colorful movie I had ever seen. For that alone it should have probably won best art direction or cinematography this year at the Oscars.

That said, what some other colorful movies that come to mind?

"What Dreams May Come"

Hero (Jet Li, not Dustin Hoffman of course)
Moulin Rouge

House of Flying Daggers

The Umbrellas of Cherbourg

Devdas

Ran

Toys
Cat in the Hat
How the Grinch Stole Christmas
Wizard of Oz
Willy Wonka and the Chocolate Factory
Pleasantville (once it becomes colorized)

Willy Wonka and the Chocolate Factory.
The Beatles' Yellow Submarine.
Danger: Diabolik.

Yankee Doodle Dandy (colorized version)

Kagemusha
Fanny and Alexander

Beetlejuice & Edward Scissorhands

Kurosawa's Dreams.

Amelie

Tears of the Black Tiger

The House Of Flying Daggers

Far From Heaven

Citizen Dog from the director of Tears Of The Black Tiger
Most of the AIP Corman Poe films from the 60's have quite garish color palettes as well.
Suspiria does wonderful things with color

Anything from Wong Kar Wai, namely In The Mood For Love, 2046, and Chungking Express.

Many of the Technicolor movies are very, very colorful. Even more colorful than most (if not all) movies made nowadays.

Bava's "Blood and Black Lace" and "Kill Baby Kill"
"Creepshow"
"Brides of Dracula"

Black Narcissus

Youse!

The Wizard of Oz popped into my head.

Beat me to it.

Three Seasons