I'm considering using Verlet.JS as a minimal Physics engine for another project of mine. I tried it out by porting over my little LSystems Crochet project to use it. You can see the results here: http://mikemoraned.github.io/lSystemsCrochet/verlet.html
It mostly works, apart from one crucial aspect: repulsion. Without it, there is nothing forcing the nodes to bunch up and form interesting patterns. The D3-based version (http://mikemoraned.github.io/lSystemsCrochet/) does this by default.
This is not really a fault of Verlet.JS, as it could probably be implemented as a constraint, but it is interesting how such a seemingly small difference can lead to such a boring outcome!
I'm gonna leave this here for now, as I most likely don't need repulsion for my other project. Give Verlet.JS a try, it's pretty easy to get going.