Books: All-time faves are Harry Potter, Good Omens, the Golden Compass series (His Dark Materials), Anansi Boys, American Gods, Going Postal, Bellwether by Connie Willis, the Wrinkle in Time series, the Lord of the Rings series, the Ender's Game series, the Tortall books by Tamora Pierce, and the Discworld books. Staples of my childhood include Little Women, the Anne of Green Gables series, A Little Princess, The Secret Garden, Matilda, Chronicles of Narnia, and Calvin and Hobbes. I also love any and all mythology, though I'm only well-versed in the Greek stuff.
Movies: I don't watch that many movies, actually, so I'm pretty easy to please. I enjoyed the new Star Trek movie and I love the LOTR movies, but other than that movie adaptations tend to annoy me. I like Road to El Dorado, Monty Python and the Holy Grail, The Princess Bride, Juno, Ocean's 11, Bourne Identity, Miracle, A Knight's Tale, Pirates of the Caribbean (only the first one), Galaxy Quest, and The Hunchback of Notre Dame. I'm still a sucker for Disney movies.
TV shows: I don't have cable, so my options are tragically limited. Right now I'm watching BBC's Merlin, Supernatural, Glee, and White Collar. I have watched every episode of Firefly, including the Serenity movie. I've also watched a lot of Dollhouse, Torchwood, Bones, House, the Office, the Simpsons, Seinfeld, and NOVA (I'm such a dork; is there even a NOVA fandom or is that just called science?). I also love Death Note, though it ended before I could see it on TV and I read the manga first anyway.
Webcomics: Kate Beaton (who does Hark! A Vagrant) owns my soul. I also read xkcd, Dinosaur Comics, Questionable Content, Lackadaisy, Digger, Dovecote Crest, The Dreamer, Shrub Monkeys, and A Softer World.
Celebrities: Mostly actors from my shows. Jensen Ackles and Jared Padalecki top this list, and I still have great love in my heart for Bradley James and Colin Morgan, but I also pay sporadic attention to Sebastian Roche, Richard Speight Jr., Chris Pine, Zachary Quinto, Darren Criss, Adam Lambert, and the gang at the CW that's always flitting into Jensen/Jared stories. Misha Collins is, as ever, a category all his own.
Active fandoms: "Active" is such a relative term. Right now, though, I'm pretty exclusively immersed in Supernatural.