Here is a little video showing what it is good for:
[vim]https://vimeo.com/55324201[/vim]
And here is the link:
https://dl.dropbox.com/u/39280733/Offse ... s.xsiaddon
note1: you can toggle offset on under Preferences > Custom > Offset Curves, or through the included toolbar. You can also doc the toolbar in your interface, like i did in the video