Bottle openers seem to be popular posts here on theNXTstep (hmmm, I wonder what that says about our readership!) and this one from R.J.McNamara is another great example.
Looks like some heavy duty gearing to get the torque necessary to unscrew the lid. What is great about this build, is the amount of information he has also posted on his website.
There are plenty of photos, descriptions and even CAD models of the different sections you can download for yourself.
Not everything was smooth sailing though! It looks like he had his fair share of 'issues' :)