Where will you be? The most prestigious of Potter fans were introduced to Harry 10 years ago as he stood on platform nine and three-quarters, awaiting his first trip on the Hogwart’s Express; a decade later, Potter mania runs rampant across the globe. Your best source for witching hour bashes is Potterparties.com; you can search by zip code, sign up for e-notices, or submit a party of your own. Barnes & Noble and Borders locations around the city have been hosting countdown discussion groups, Hastings festivities will include trivia contests, prizes, costume contests, and sorting hat sessions, and the Central Library will be transformed into Hogwarts as 100 lucky party-goers will get to check out copies of the book at midnight. But don’t bet on seeing Hagrid — he’ll be at Arachnocon.