Brigs seems like exactly what I was looking for. I'm trying to rig a snake and want to put nulls on a spline and slide them there so that they maintain their distance.
But I can't figure out how to use this tool.
I got it installed but when I select the nulls and the curve and hit Null 2 Curve, it just creates a new null that doesn't do anything.
Also, there was no example for Null 2 Curve in the project files.
EDIT:
Sorry about that, I guess it's just that it has to be a linear curve. I tried to use spiral and arc.
Finally found a tutorial video for this:
https://vimeo.com/12377832