The 2D Lemniscate of Bernoulli example proved to be rather popular, so I thought a 3D extension would make a good test for the 3D closed-loop Catmull-Rom spline. This example animates a series of markers (boxes) along three figure-8 paths in the XY, XZ, and YZ planes.
Arc-length parameterization produces smooth motion along all three paths. The online demo may be viewed here, which includes a link to download the entire Singularity package.
The Algorithmist 
pretty cool – any plans for a Flash/AS 2 version?