Experimental interface for entering "numeric bands" in response to this User Interface StackExchange question
There's an online demo you can try out. Bear in mind it was written in an evening, and was my first jQuery program.
It's MIT licensed...in case anyone feels there's a reason to borrow anything from it!
UPDATE 20-Mar-2015 I have wound up revisiting the script briefly on a couple of instances to keep it working as the site has changed. Most recently, that was to add the overview video.
Source code is available on GitHub: