RJ11--common telephone wire--is common. Probably everyone on this board has a mile or so of the stuff laying around from various sources, and the connection is somewhat simple--line up the colors, and slip on the crimp connector.
Would there be anything to consider if using it for general plugging stuff together on a project? I'm not sure how much current it could take, but for situations where you want to be able to plug stuff in and out frequently, or swap boards and components easily, it would be a lot better than jumper wires or digging through Digikey for the pins and stuff to make your own servo style connectors, and would look neater too.
The big thing I was seeing was how easy it is to find the cable, and cut it down and put connectors on it.