I mostly spend my spare time with my computer or books. Other than those, I occasionally waste my time with television, movies, music and alternative stuff.
I guess other than my computer (about which I will talk separately) which is my first passion reading remains my favorite hobby. I read about one book every fortnight.
Other than reading a lot of books related to my profession, I love speculative fiction (some people also call it sci-fi and fantasy). I believe sci-fi allows an author to make incredible social commentary which is not possible in any other genre. Isaac Asimov (in particular, his Foundation Series) stays my favorite in spite of so much I have read after it.
I do not read a lot of "popular fiction". That means I am not much into common "thrillers" and "horrors". So, stuff like Stephan King, Fredrick Forsyth, Jeffrey Archer or Robin Cook is not for me because I find the authors too typed and their books too predictable. Occasionally, one of these books is well-written (which I then try to read).
However, I enjoy interesting science books (say A Brief History of Time or Godel-Escher-Bach). Talking of GEB, Hofstadter is among my favorite writers. ( I have actually read GEB a total of 8 times !) and Cognitive Science my favorite "side-area" of learning. I have always been intrigued by the ways and means of developing computational models of brain and "attempts by mind to model mind".
I also read a little too many magazines and newspapers. I love reading about current events, what they mean, how they happened and what they will lead to. My concerns are always philosophical and social. I love discussing and pondering over the nature of life, the universe and how it all came about and its meaning if any. I haven't yet figured out how it all adds up to 42 though. (And if you understand that reference, you can guess what kind of humor I like). Douglas Adams is one of the funniest writer. I have read Hitchhikers' Guide To The Galaxy and Restaurant At The End Of The World probably half a dozen times each.
Talking of humor, I can also read comics anytime. Calvin and Hobbes, Tintin, Garfield, Astrix and Snoopy are my favorites.
While we are on humor lets cover TV too. Humor shows are about the only thing I do not like to miss on TV. I love absurd humor, so Mr. Bean and Cyrus' MTV Bakra are my favorites. I believe that the best humor is that makes fun of ourselves and our stereotypes.
Other shows that I occasionally watch on TV include Friends, Dharma and Greg and Everybody Loves Raymond . Talking of these you can easily guess my favorite channel is Star World. I also enjoy history and science documentaries on Discovery and National Geographic. I find them pretty well-made and informative. I have also started watching a whole lot of movies on HBO lately. You can read more about the kind of movies I like.
As long as we are here, lets talk about music. I love almost all kinds of music except hard rap, heavy dance or screaming metal. I usually leave my TV on MTV (the biggest music channel in India ) when I cannot find anything interesting anywhere else. I also cannot drive my car unless music (from FM or cassette) is on. I have a large collection of MP3 encoded songs (on my hard disk and network) - encoded from my CDs - and I regularly play them while working. I also have a lot of music on cassettes but I cannot hear to it (unless I am in my car) because I do not have a decent music system (I gifted mine to my sister) and I hate walkman. I plan to find a way to plug my walkman into my soundcard and hack it all someday.
Other than all this, I also do a whole lot of alternative stuff. I was very actively involved with some of the most 'heavy' and super-secrets cults that exist in this country and they have given me experience and memories which very few people would have had in their lives but I would rather not go into it here.
However, I have left most of that for good and indulge myself only in the 'lighter' stuff now. I am an astrologer and palmist of some repute. I even took the trouble to do an year-long study of astrology at Indian Institute of Astrological Studies (Yeah, in India, they have institutes that do that!!). I also meditate a lot and am deeply interested in Zen. Zen has helped me changed in many ways and made me unlearn a lot. Reading and collecting Zen koans is one of my hobbies. You can read a few of my favorite koans here.