This is a really simple (and kind of cheap) way to ensure as little link overlap as possible in a force-directed graph. It is inspired by Moritz Stefaner's Force-based label placement, where he uses invisible nodes to avoid overlap of text labels.
In this example, I've taken the classic force-directed graph example of the Les Miserables dataset, and made two simple tweaks: I use the links array to calculate the invisible nodes, and place the nodes at the halfway point of each link. Conceptually, it is very similar to Mike Bostock's Curved Links.