The PQ-Torus, or PQ-Torus Knot, is a parameterized version of the well-known Torus (A donut-like geometrical shape).
P and Q are two parameters we use to modify the toruse's shape.
The first place I saw a PQ-Torus at was : http://www.blackpawn.com/texts/pqtorus/default.html, they have some nice screenshots and a downloadable implementation of their PQ-Torus.
There is a small toolbar through which you can control the toruses' parameters, including P, Q, Radiuses and Texturing mechanism.
I used my own approach to generate Normals for my Torus in real-time, which allows real-time wiggling, jiggling and morphing of the torus.
The nicest feature is the ability to shift P/Q values and watch the torus morph from one state to another.
Here's the link: http://ohad.visual-i.com/exper/exper.htm#pqtorus
Ohad Eder Pressman