One thing I've been thinking about for years, is flexible robots. I'm a pretty good fabricator, but the precision and complexity, required to make useful multi-degree of freedom joints (like your shoulder) has always seemed a little daunting, especially if you try to make them compact.
Some time ago Erin Kennedy, a brilliant, creative, visionary robot builder, and long distance friend posted a couple of tidbits on a tentacle mechanism she was pursuing. The first iterations I saw were 3D printed parts connected with machine screws. After seeing a video put out by the folks who make Sugru illustrating the use of 3D printed parts as molds to form Sugru parts, I suggested to Erin she try using Sugru as a flexible link between her 3D printed parts. The folks from Sugru caught wind of the project, and donated some material to the cause, and Erin ran like mad, quickly bringing the idea into a working model.
Shortly after Erin worked out her design, she started offering 3D printed parts for sale. I immediately placed an order, and was quickly rewarded with dozens of electric green and orange parts, direct from Erin's lab.
That night I cast a couple of links, and in the morning had one good one to start with. The other one stuck in the mold, and tore coming out. Once again, let me shout out to the folks who make Sugru, they sent me a donation as well, and I'm finally putting it to good use.
This weekend I used Sketch-up to design a framework, cut the parts on my ShapeOko, and TADA - Flexibot 0.1 is born.
Right now I've got the servos hooked up to an RC receiver, and I'm just driving it around with the joystick on my transmitter. This is just the beginning, and once I get a little further on the mechanics, I'll turn it into a proper robot with autonomous control.