There's been a few threads on this forum about swordsmanship. I'd like to offer another...kyudo (Japanese archery).
I've been training for just over a year now, and I love it. It's far less aggressive than some of the other arts (a little more like aikido in that respect, perhaps). I hate kiai-ing, so that's another nice aspect for me. It's highly technical - the smallest error in technique will throw off your aim - and demands intense concentration (while paradoxically also requiring that you empty your mind while shooting...go figure! )
If you haven't tried it, I thoroughly recommend you check out kyudo, because it's hard to explain how much satisfaction you can get from hitting a small target with an arrow!
Are there any other kyudoka amongst the listeners?