1. Relatively recently: western martial arts. Like longsword fencing and such. It's so awesome and uncommon, and there's some rich historical background and participation in it. There's a gym for it maybe 20 minutes away, but really it'd be tough for me to make a commitment to taking it on now. Most likely a bit too much time/distance for me to actually stick with it even if I went for it. 2. Bass. Freshman year of HS I got the unusual idea that I wanted to be a bass player. Within a month or two from the first time I had that thought I got a bass and taught myself to play. It's been a big part of my life ever since and was totally worth it.
On 1: I've done martial arts for about a year (kyokushin karate) and what I've noticed is that you can often take a tryout lesson for no (or a small) fee. No commitment necessary, they are often very hospitable to potential members. Maybe send the gym a mail to ask? Can't hurt much, and martial arts are really cool.