I'm just curious what sort of stretches you guys do in each of your styles.

In my fencing class, the majority of the time is spent on leg stretches, going from a left footed lunge position, then rotating the back foot to point on the toe and putting the hand under the leg, then turning to have the left foot flat on the ground and the right toes straight up. Then, rotate again so that the knees are together, you are sitting on the left foot, and the other has the pinky toe on the floor. Finally, push up with the back leg to stand with both legs straight and both feet flat on the floor, left toe pointed to right heel. Lunge with your right foot and repeat.

Each position is held for about a minute, coming out to ten minutes for the leg stretches.

What about other arts? Is kenjutsu more focused on stretching the arms? What about Kung-Fu?

We stretch our entire body in Kung Fu. Swords, or not. With a complete stretching program, you shouldn't need sword specific stretches. Those muscles should be flexible for striking anyway.

Oh yeah, and I fence also. After a real Chinese stretching program (three actually, lol), I can honestly say, "No athletic activity has ever posed a challenge to my flexibility." Though I haven't tried contortionism yet, lol.

Personally, I don't think traditional stretching is as beneficial before training as after it. Standard passive-static stretching exercises weaken the target muscles up to 20% for about two hours. this leaves you prone to injuries while training. For this reason, I recommend a short warm-up and dynamic stretching exercises to start with. Save the passive stretches for after the wind-down (end of class).