My obsessions would have to be the following:

My reptiles - I can never seem to have enough. I always want more.

My computers - same thing. Maybe that's why I have 4 of them at the moment, and my own server rack with a kvm switch, and a 24 port network switch... However, I seem to be able to cap out at 4, and I don't have any urge to buy more

The internet - I'm on it all the time, and hopelessly addicted.

That's about all I can think of at the moment.