Aside from the obvious...
Movies - I'm a big movie buff and I like collecting VHS and DVD.
Books - Non-fiction and fiction. Collect them as well.
Animals - learning about them, big Animal Planet/Discovery viewer.
Interior Design - friends tease me about my studies into Feng Shuai
Landscaping - just the design and concept - forget about really doing it.
Music - love collecting music - all kinds.
Wine tasting - when I can afford it.
Computer gaming - am an old gamester.
Bookstore browsing - I can spend a good hour or two just looking.
Chess - don't have playing partners like I used to do and hate playing online.
Travel - I usually enjoy weekend getaways.
Surfing the Net - yep I'm a net-aholic.
Collecting porn - and I'm damn good at it too

Knife collecting - I love bladed weapons, fantasy knives, swords, etc.
Broadway Shows - don't get to these as often as I would like but enjoy the theatre.
Politics - who would of guessed? Yes, I enjoy debate.
Researching - call me wierd but if it is something I like or want to know more about, I like to do research.
Art - just getting into art over the last couple years and enjoying it. Looking at it not doing it
Writing - despite my bad language and English skills, grammar, etc. I love to write. Between 1983 - 1989 I had 139 by lines to my credit, mostly for articles written for our local weekly newspaper I wrote for. Lot's of time off between my next publishing works which started in 1998 again and since then and present I have written and published over 20 articles.
Would love to start as a hobby and will when I can:
Home brewing - both beer and mead.
SCA - the medieval re-enactment group. Haven't been active in awhile unfortunately and need to start going again.
Toastmasters - will probably be starting next month.
Art Collecting - sorta already started this, but it is a slow, slow process.
Well I think I covered just about everything...
Sam