Cleaning my M4. Regular cleaning (my room, the tent in general, policing up doneage after a fire mission) doesn't appeal too much. But when it comes to my rifle, it gives me a very zen calm. Maybe it's because of how meticulous you have to be to get it squeaky-clean, maybe it's because I'm maintaining a piece of equipment that could be vital to my existence, but it's still a rather enjoyable activity, even though it's something I do once in a great while.
I find it a little strange that I get a charge out of helping others with computer problems. I'm one of the tech guys in my platoon, and when someone comes to me with any kinda computer question, my brain starts doing a little dance. A few weeks back my section chief's laptop crapped out, and even though he was a tech-support headache, I still really enjoyed identifying, attempting to trouble-shoot the problem, and laying out the alternatives since his computer (the HDD, to be specific) was beyond saving.
Furthermore, I even go so far as to fantasize (I'd be fooling myself if I used any other word) about helping others buy or build a new computer, given certain imaginary limitations.
Incidentally, I qualified this as only a "little" strange, since computer savvy is in my family, especially my father. I just take after my old man like that, I suppose.