One example is calculating a straight skeleton. You can do this with a Laplacian node followed by a Linear Solver set to "SymEigsShiftSolver". This gives you a bunch of Laplacian eigenvectors, which are like frequencies making up a mesh.
The second lowest frequency (or eigenvector) is called the Fiedler vector. It follows the general flow of the geometry, which is great for straight skeletons. Also it's orders of magnitude faster than Labs Straight Skeleton 3D!
Thanks to White Dog [x.com] for letting me share this and suggesting improvements! It's based on his Curve Skeleton example [drive.google.com]
Download here:
https://github.com/MysteryPancake/Houdini-Fun?tab=readme-ov-file#-hda-fast-straight-skeleton-3d [github.com]