The virtual card honoring Apple’s (AAPL) CEO is the handiwork of computing students at Imperial College London. “Our aim,” write ringleaders Raoul-Gabriel Urma and Gabriel Lorin, “is to allow as many people to wish him a happy birthday this way letting him know he has a back-up of so many.”

You can add your message here.

UPDATE: By the time Urma and Lorin closed the post — 53 hours after it opened — the card had attracted more than 74,000 visitors and 20,032 birthday wishes.

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[Follow Philip Elmer-DeWitt on Twitter @philiped]