there is Bitcoin Pizza Day which is celebrated on May 22. as you now Laszlo Hanyecz bought two pizzas for 10 000 BTC and this fact made bitcoin famous. I think this purchase made very much for promoting bitcoin.
Oh, really? I didn't know that fact. Well, there's nothing wrong if we're gonna promote btc by considering the suggestions of OP, having a celebration of International Bitcoin Day i'm sure people will get too curious about btc. That way, digital currencies will spread all over the world.