This has been done a few times before:
http://www.iceinspace.com.au/forum/s...ad.php?t=35352
http://www.iceinspace.com.au/forum/s...ad.php?t=60589
http://www.iceinspace.com.au/forum/s...ad.php?t=92795
And I think buried somewhere in those threads I may have said something like "I have too many to list!"
I may have also muttered something along the lines of "not enough time and money!" too
Edit:
Expanding my reply:
Home brewing (All-grain) & collecting beer glasses and beer/brewing nostalgia
Home machining (lathe/Milling machines)
Storm chasing
Photography
Surfing (real, but yeah, web too

)
Driving (I just enjoy going for a random drive sometimes)
Bonsai
Electronics
Model planes/boats/cars
loudspeaker design/building
Also, combining the above is very enjoyable... Astro+Photography+driving+machining +electronics(+beer)
or Models+photography+machining+electr onics(+beer)
the list goes on... many of these interests get neglected for long periods, like I said, not enough time or money