A collection of SPAM cans began as a joke.

SPAM® collection, as of June 2007:

http://www.alaska.net/~royce/spam/

Click to Enlarge

The three seemingly duplicated Golden Honey Grail cans are actually three variations:
The empty one handed out at the New York debut of Spamalot
The full can available only from the factory
The full one for sale at the Vegas show
And some non-can extras:
http://www.alaska.net/~royce/spam/