I share your enthusiasm for hiking and photography, and often like to combine the two. Here are some photos from my recent trip to Yellowstone:
Yellowstone Photos
This goes well with my enthusiasm for bird- and wildlife-watching, which I picked up from my dad when I was a kid.
Of course, I also play a lot of video games (though probably not as many as some folks on here). I tend to like RPGs and action/adventure games and spend a lot of time playing games on the classic consoles (NES, SNES, etc.). I keep up with the video game scene, but try to limit the time I spend on it, as my obsessive personality can lead to addiction with certain games.
During the summer, I like to play softball. I was the head coach for my department team (again, in grad school) and I'll play any position I'm needed at -- they usually put me at shortstop or outfield
I'm one of those people with a short attention span for hobbies, so I've dabbled in a lot of other things over the years, including politics, philosophy, web scripting, etc. Really the only thing that has consistently kept my attention is songwriting. I have a large collection of songs (though very few recordings) and I was the singer/songwriter/guitarist in a band in grad school. I haven't been active in the music scene for about a year, but I'm always trying to come up with stuff in my head. Aside from my girlfriend, family, and work, music is probably the most important thing to me.