This JSConf.Asia 2013 talk about NodeJS in Photoshop [1] is very good as well, e.g. "Generate > Image Assets" is a Node script that automatically extracts PNG & JPEG when the PSD is saved, so combine it with gulp watching the output folder to livereload images of the site you're testing by editing a PSD: imho that will sure help designers work with programmers.

The "OK Photoshop" demo is just hilarious :)

[1]: https://www.youtube.com/watch?v=wqmMqB91zdI