Regular Graphs Page Tables of simple connected k-regular graphs on n vertices and girth at least g. http://www.mathe2.uni-bayreuth.de/markus/reggraphs.html
The Four Color Theorem Computer aided proof of the four color theorem by Neil Robertson, Daniel P. Sanders, Paul Seymour and Robin Thomas. http://www.math.gatech.edu/~thomas/FC/fourcolor.html
Signed, Gain and Biased Graphs List of publications and manuscripts annotated by Thomas Zaslavsky. http://www.math.binghamton.edu/zaslav/Bsg/
Multicommodity Problems Instances and random generators of multicommodity flow and network design problems. http://www.di.unipi.it/di/groups/optimize/Data/MMCF.html
Graphnet Archives Archives of the Graphnet mailing list from February 1990. http://listserv.nodak.edu/archives/graphnet.html
Traveling Salesman Problem These pages report the history of the TSP and ongoing work to solve large instances. http://www.math.princeton.edu/tsp/
BHOSLIB Benchmarks with Hidden Optimum Solutions for Independent Set, Vertex Cover, Clique and Vertex Coloring with datasets in DIMACS graph format. http://www.nlsde.buaa.edu.cn/~kexu/benchmarks/graph-benchmarks.htm
Knight's Tour page of Links Collection of links and references by Mario Velucchi. http://www.velucchi.it/mathchess/knight.htm
Four Colour Theorem A new proof of the four color theorem by Ashay Dharwadker that uses group theory and Steiner systems. http://www.geocities.com/dharwadker/
The Hamiltonian Page Hamiltonian cycle and path problems, their generalisations and variations. http://www.densis.fee.unicamp.br/~moscato/Hamilton.html
Knight's Tour Problem Solution for chess boards with upto 32 squares. http://www.tri.org.au/knightframe.html
TSP Generator Generates a Traveling Salesman Problem map and data for a given set of US cities. http://www.sju.edu/~sforman/research/usa_tsp.html
A Constructive Approach to Graph Theory Notes on a semiotic approach to constructing isomorphism invariants of graphs by John-Tagore Tevet. http://www.hot.ee/tewet/