I don't have much time for hobbies these days, with a 5 year old boy and 21 month old girl running around. Not so much money either.
I'm somewhat into A/V, in so much that is where most of my share of disposable income has gone, but photography is aiming to eclipse that. My A/V system is a compromise between 2 channel music and surround sound for movies.
At one point, I had considered getting into speaker building, but we started a family soon after that. I did build the subwoofer, just a month before our son was born. It's my least favorite thing in my system, mostly because it is not particularly "musical". Response isn't flat enough and it can be boomy. It sure can shake the room. For $200 for the plate amp and driver, and $100 in misc parts and MDF, it's incredible. My next investment will hopefully be a Rythmik Audio 15" active servo sub, mostly because I can't afford something like a Velodyne.
We have a fair collection of movies; about 250 titles. Purchases slowed greatly once we had kids. We don't go see movies as often, and can't keep a good pace with Netflix either, so I don't generally know what to buy.
Music has suffered more, and that bothers me more. We have well over 500 CD's that I ripped to FLAC. It gets played through a Slimdevices (now Logitech) Squeezebox, which is absolutely fantastic. I just don't know what to buy anymore and rarely have time to just sit and listen ('though I make myself do so occasionally and never regret it, other than the inability to choose.) Anything on the radio is either garbage or over played. Anyway, we bought probably 490 of those CD's between 1990 and 2000 and have only bought about 30-40 since.
I'm also a car nut, but you wouldn't know it by looking at what we drive: a plain "low-option" minivan and a 100% stock 1/2 ton 4x4 truck. If I can ever stop spending money on A/V gear, photography gear and daycare, that will hopefully change. Meanwhile, I've been building up my tool collection, so I'm ready for a restoration project in the future.
Ahh... forgot the other money pit: Home improvement. Not so much a hobby as me being handy + cheap.