Thanks for cleaning up some examples!

I think the fahrenheit/celsius scale example is more or less ready to go. (I had some minor comments, but nothing major.)

The barchart examples may need a bit more thought. The original example showed a few more features than just error bars. I'd be inclined to split the example up into barchart_demo and barchart_demo_features, where the latter retains more of the features of the original. In fact, barchart_demo.py in examples/pylab_examples (not examples/api) is a pretty clean version of this example.

As suggested in the MEP12 guidelines, you need to check whether the examples you move are referenced in the docs. I believe barchart_demo.py is referenced in the backend_driver tests. Also, you should consider running a PEP8 checker just to ensure you don't miss anything.