Good thread.
I guess in chronological order going all the way back to high school - just don't get time for many of these anymore with work and family....
Reading - SciFi in particular - would hate to count how many books I have stashed around the house, and a fair proportion of them were traded in over the years too
Fish (goldfish mainly - used to breed and keep in a cemented old water tank in back yard - multiple tanks indoors, big one in the living room). Haven't had fish for many years though.
Astronomy - got hooked at a school camp
Cycling - mountain bike and road bike - not sure I could make it down the coast any more though....
Sailing - windsurfing for nearly 20 years, part owned a trailer-sailer with friends in which we used to knock about Moreton bay. Friends have a 36 footer now, but didn't want to "sink" that much money into boating.
Diving - not for 10 years, but used to dive in the bay and on Flinders reef regularly
Keyboards (piano, electronic organ, PC music, audiophile interfaces, midi controller keyboards, KRK monitors, VST instruments, other computer applications, etc)
Computers - particularly for music and Flight simulation (and astro)
Would love to be able to afford to fly. Got as far as going solo and getting a student licence many years ago, but just too expensive. Still get a buzz whenever the wheels leave the ground for a work flight though.
Astronomy - Rediscoved 2 years ago, and very promptly became addicted to astrophotography in particular. Now I can finally "see" some of those blasted galaxies I was always looking for. Probably would have had a lot more success if IIS was around 30 years ago....
Wife and I have decided not winning lotto is seriously holding back our hobbies dammit!
(I think a property a few hundred kms west with a personal airstrip would be nice every month or so so I could extinguish my astro needs - I could probably fit a few friends in if I win enough

)