I use this cable:
http://btpa.com/CA-0363.htmlIt's ultraflexible subminiature quadmic cable (designed for making custom mini-XLR cables for field recording). I mainly use it because it's got similar size and electrical properties to the mogami version (which you can only get a whole 1000 ft roll of) which is rated for like 20,000 flex cycles (way more than a normal USB cable).
There are a few problems with using this cable.
1. It's really small. This make sit hard to strip. I recommend getting a dedicated wire stripper, as using a knife sucks.
2. It doesn't support much weight. You have to make sure you crimp your strain relief really well on both sides. I also strongly recommend using cable sheathing to further increase the tensile strength.
On the plus side, it's really flexible, works well, is cheap, etc. This is my fav. cable to use for USB stuff.