My main hobby is probably collecting comic books. Now that I'm living in Japan, I have my good ol' local comic book shop ship my comics internationally so I can keep up with mah stories!
Action figures are another vice of mine. I actually had a whole room of my house in the States dedicated to displaying my collection. It's kinda sick. Now my precious hoard is all packed up in boxes in my mom's basement.
I play video games when I have the time, but who doesn't these days? I'm mostly into Nintendo, but I play this really neato super hero MMORPG called City of Heroes when I can afford the subscription cost.
I also really enjoy going to thrift stores, consignment shops, antique stores, and especially yard sales. Here in Japan, I try to hit up the recycle shops and flea markets. You never know what you might find!