Combinatorics Problems - Combinatorics problems selected from math olympiads. www.geocities.com/CollegePark/Lounge/5284/math/combinatorics.html
Open Problems for Undergraduates - A collection of open problems in Discrete Mathematics which are currently being researched by members of the DIMACS community. dimacs.rutgers.edu/~hochberg/undopen
Past Open Problems - From the SIAM Activity Group Newsletter in Discrete Mathematics. In PostScript. Compiled by Douglas B. West. www.math.uiuc.edu/~west/pcol/pcolink.html