Braid Information Adam Chalcraft's website about braids and the braid index of knots.
More Braid Information Thomas Gittings's paper "Minimum Braids: A Complete Invariant of Knots and Links," giving minimum word lengths for braid representatives of knots.
Knotilus A website built by Stuart Rankin, Ortho Flint and Bruce Fontaine which provides for diagram creation for knots and links, either by giving a Gauss code, or in the case of knots, a Gauss or Dowker code, or if applicable, by giving the Rolfsen or Thistlethwaite number of the knot or link, or sketching it in the provided Java-based annealer sketchpad. Code for the diagram may be downloaded in a variety of formats (TeX, Postscript, PDF, PNG, and POVRay). If a Gauss code for a reduced alternating diagram of a prime alternating link has been given, then several properties of the link will be returned along with the diagram. Included among these properties are the symmetry group of the link, the number of inequivalent orientations of the link, amphicheirality (both unoriented, and the number of orientations that are amphicheiral), and, if a knot, whether it is invertible. From the main page of Knotilus, one can browse and select for drawing any of the more than 98 billion prime alternating links at or below 23 crossings.
The program Snap is a valuable resource for knot theoretic computation.
Slavik Jablan and Radmila Sazdanovic have created the site LinKnot offering online computation of a large variety of knot invariants.