This hour long conference lecture by Bret Victor is a really fascinating look at how to change the way engineering professionals create what they create. He experiments with some simple yet powerful tools to show what creative tasks could look like if they provided almost instant feedback to their creator. Most of the examples relate to software engineering and the languages used are either in JavaScript or Java.
Update (6/7/2014):
I recently came across Light Table which is a next generation IDE which displays code right next to a browser window. You can then modify the code and it is updated within the browser in real-time.