[sciguy125]

Geez, you read a post, decide to reply later, and got to sleep for 8 hours, then Al takes your idea...

Anyway, consider a chain, like roller chain that would go on a sprocket. Put it on a table with the pins perpendicular to the surface of the table (ie if it were on a sprocket and the sprocket was lying flat on the table). With the chain straight, run a cable along the side. Put some sort of guide on each link and attach the cable to the upper link. If you pull on the cable with your actuator, it'll curl in the direction of the cable. Now, run a cable on the other side of the chain and keep your "tail" curled in this direction using a spring. If you were to completely relax the actuator on the first side, the "tail" would naturally curl toward the spring side. You can then use the actuator to straighten it by pulling the cable on its own side. You can now make it curl in both directions using only one actuator. This however, would only get you one big curl, not the snake-like motion you wanted.

You only asked how to curl it in one plane, but I wanted it to go in the perpendicular plane also. To make it curl perpendicular to the table's surface, you'd need the other actuator (which is why I only used one above). Obviously, you'd also need to find a replacement for the chain because it doesn't bend in that direction. If you put the same cable setup in the perpendicular plane, you now have 3-D range of motion.