Taekwon-Do as my main art (did WTF, went away, now am for about 6 years in ITF Taekwondo), but I add a lot of self invented moves. A pity I'm not allowed to use them in training fights. We have a lot of fun together, so I really enjoy that club, great people!
Thinking of taking a bit of Aikido in Summer, because I want to improve my ability to catch hits and kicks in mid attack and then break the arm or leg.
I also train with a Jo (128cm white oak hitting stick), it's truly a great thing! I add it as an additional leg (hey, two legs hitting at different height at once!) and have self-invented some really nifty moves.
Also a lot of useless ones that serve only to look good, then the fight with a shadow looks more like a dance, what I really enjoy too, most enjoyable activity!
That said I don't really train for fighting, I have quit tournaments (they're too artificial) and I've always have trained because it makes me feel really good.
I like to be able to hike, kick, jump, fly, run a few steps on a wall (matrix style),
it makes me feel really, really alive.
If it helps me a bit with self defence - I don't mind, but that's not why I'm in for.
oh and a trivia
I frequently train at my room while waiting for replies at Sciforums - like right now