Plenty. I like mucking about with swords. Kendo, iaido, fencing. All fun.
Started at a 'Kung Fu' school, which was a blend of Tae-kwon-do and Southern style Shaolin boxing. Did 5 years before being encouraged to leave for putting another student in hospital. I too may possibly be naturally violent.
I cannot thank my Sifu enough for the care he took in training me.
A 'Self defense Academy' for 4 years, training a combination of Muay Thai, professional kickboxing, street defense and good old karate. And Escrima, which is the noise you make when your fingers break. It moved, and I didn't.
Oh, a small stint with the Ninjitsu schools in Australia. Embarrassing, and nearly resulted in a criminal record. I left when a friend had a femur shattered during an 'exercise'. Stayed to be beaten for not being thinner though. Go figure.
I cannot recommend Caepoeira or Aikido enough, for their conditioning and attitude respectively. I like that Caepoeira puts you in a Ronda as soon as you can Jinga, and I like the calmness and elegance required to defeat a much more heavily armed opponent that Aikido engenders.
I'm worried that a number of people here don't consider Judo to be particularly martial. Any art that requires techniques to be performed well so that you don't kill your practice partner out of hand definitely falls under the martial category. It's designed to kill heavily armored opponents, and it is highly effective at it.
One teacher recommended ballroom dancing as a training technique. You'd be surprised at the improvements it generates. You also meet girls/guys who don't hit you on a regular basis. It's fun.
Jeet Kun Do, as the creation of the premier martial artist of our time, deserves careful contemplation. Tai Chi Chuan is commonly underestimated, and I would like to study Pa Kua Chuan and Hsing I. Good teachers aren't all that easy to come by.
That's what SageSays