[Shoubuliao]

My favorite is the heavy Thai style rope for the shoulder conditioning benefits. Twins makes a really good one.

You can also make one of these on your own with just a piece of clear tube from the hardware store, couple of PVC pipes for handles, and a bolt and washer to hold things together. This guy did a nice overview:

http://rosstraining.net/forum/viewtopic.php?t=71181