Looks like the USPS website uses the google search appliance. I was messing about with the search url and turned this up:
Go to the search form and enter a search for a package.
At the page this takes you too, go to your address bar and erase everything after ?q=######## where ####### is your package search number.
You’ll see the secret easter egg usps google home page.
But wait, there's more
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