This is a compilation of DesignByNumbers' ropelength minimising knots, arranged into a single file for the thin versions of the knots, and a single file for the thick versions. These are all of the prime knots with at most 7 crossings.
Each knot is tied in a tube of constant radius, and pulled tight. In the thin version, the tube has been reduced to half-size in order to help you see the crossings. In the thick version, the tube appears at full scale.
For more information about tight knots, see http://en.wikipedia.org/wiki/Ropelength.