DARPA's Maximum Mobility and Manipulation (M3) program recently demonstrated low-cost silicone robots with microfluidic channels that allow for air and fluids to be pumped in to control movement, color and temperature.
Take a look at the following video, which shows a soft robot going for a walk on rocks.
(DARPA Maximum Mobility and Manipulation robot video)
The robot moves at a speed of approximately 40 meters per hour; absent the colored fluid, it can move at approximately 67 meters per hour. Future research will be directed at smoothing the movements; however, speed is less important than the robot's flexibility. Soft robots are useful because they are resilient and can maneuver through very constrained spaces. For this demonstration, the researchers used tethers to attach the control system and to pump pressurized gases and liquids into the robot. Tethered operation reduces the size and weight of such robots by leaving power sources and pumps off-board, but future prototypes could incorporate that equipment in a self-contained system. At a pumping rate of 2.25 mL per minute, color change in the robot required 30 seconds. Once filled, the color layers require no power to sustain the color. "When we began working on soft robots, we were inspired by soft organisms, including octopi and squid," Morin said. "One of the fascinating characteristics of these animals is their ability to control their appearance, and that inspired us to take this idea further and explore dynamic coloration.
Science fiction fans recall the moldies from Rudy Rucker's 1997 novel Freeware which featured robots with remarkably flexible forms:
Monique was shaped more or less like a chessman with arms, like a pawn or a queen or a knight. The exact appearance of her humanoid head and arms was something she could tweak...In [her] alternate "pelican" mode, Monique became a set of great flapping wings attached to a tapered big-eyed body... Monique's tissues had at least three other basic attractor modes as well: the spread-out "puddle" shape she used for soaking up sun, the seagoing "shark" shape, and the rarely used "rocket" shape that moldies could use to fly back and forth between the Earth and the Moon.
(Read more about Rucker's moldies)
Be sure to take a look at Technovelgy's DARPA Project List, the biggest list of DARPA's science-fictional technology available.