Besides Williamsburg of course, I think Greenwich Village really won me over. It was perfectly cold and grey and I visited Bob Dylan's old haunts, it was great (first photo is Jones St. - cover of The Freewheelin Bob Dylan album).
Also, at a cafe in Brooklyn I bumped into a friend that I knew from my hometown (seriously Santa Barbara follows me everywhere I go!) and met up with him on my last night to visit Times Square, the Empire State, to see Central Park at night complete with huge NY rats, to see the crazy Christmas window displays, and to spend some time hanging out at The Ace Hotel.
New York was amazing. I am going to move there after I get my BA in May.