It performs both analytic and numerical manipulations of knots and braids. A Circular History of Knot Theory - Starting with the flawed theory of Kelvin's knotted vortex to the work of Thurston, Jones and Witten, knot theory has circled back to its ancestral orgins of theoretical physics. Cook's Borromean Ring Links - Links to pages about Borromean rings and two outlines of proofs that show the Borromean rings can't be made from circular rings. The number of different Alexander, Homfly and Jones polynomials for knots of up to 15 crossings is given. The algorithm has a better time bound for large links than algorithns that ignore duplicates.
Source code is on the site.
Geometry and the Imagination - Has a small section on knot theory at an introductory level. Also has sections on orbifolds, polyhedra and topology. Knot Theory - A page of links on geometric questions arising from knot embeddings. History of Knot Theory - Biographies of early knot theorists. An Introduction to Knot Theory - Introductory level tutorial requiring only a high school mathematics background, some linear algebra is needed in places.