In the past I have seen panels for Hellboy, Wanted, The Chronicle of Narnia: Prince Caspian, The Hurt Locker, Dollhouse, Watchmen, Fringe, Friday the 13th, Terminator Salvation, Nikita, The Vampire Diaries, The Thing, Battlestar Gallactica, Hanna, and Your Highness.
Vampire DiariesEach day is extremely long but completely worth it. Its great to hear the thoughts and ideas from the creators and actors of these tv/films. You get to learn crucial information about where a tv series may be heading or see 20 minutes of a film long before it will hit theatres.
Besides the tv/film part there is also a huge gaming following at NYCC, a massive amount of signings, shopping from hundreds of retailers, so much free stuff or special edition things you wouldn't believe, and it also holds the Anime Festival.
It wouldn't be Comic Con without costumes. You will see every type of costume you could ever imagine (though superheroes definitely take the cake). Don't worry! You don't have to dress up to fit in, there are plenty of people not in costumes as well.
I highly recommend attending if you are in the tri-state area, if you're not, there are tons of travel accommodations that NYCC will help you with. For more information click HERE.