Aside from guns, I'd say the closest "passion" (or OCD) would be guitars and keyboards. Favorite 6 string is a Dean DCR Razorback #56 of 100. Pro guitars are much like firearms in the way they hold value. Been playing live music for over 12 years now and met many, many folks with the guitar/gun combo passion. Like Uncle Ted for instance... I play guitar every day.
Love my Pentax for photography needs. Nothing wrong with Canon or Nikon - I have just had excellent results with Pentax.
Binoculars & Spotting scopes as well as rifle scopes. Leica, Swaro, Burris, Vortex. Gotta have 7x, 8x, 10x, 12x plus spotting scopes... Burris Eliminator Laser Rangefinding scope, all sorts of red dots, etc. for these old eyes.
1995 Mitsubishi 3000GT VR-4 AWD AWS twin turbo for sports car needs
2010 Ford SVT Raptor 6.2L (world's greatest off-road truck)
2006 Honda Rancher ES quad - work/recreation/hunting vehicle
1998 Honda VFR800Fi Interceptor - gear driven cams, fast...
Always thought boats were too much expense
Used to have my pilot's license but flying is worse than floating/sinking
My wife thinks I have more camo gear than anyone she's ever seen. If it is made in camo, I've probably bought it. Tons of hunting gear.
Used to be a pro snowboarder so I've got 18 snowboards, tons of gear for both the wife and I, alpine skiing stuff as well.
Job has me in to whatever computers I want/need so I don't even really consider computer/electronics in the equation.
Serious coin collection
Serious stamp collection
several nice wristwatches