Some Open Problems
- Kézdy's open problems.
- http://www.louisville.edu/~aekezd01/open/open.html

Perfect Problems
- Unsolved problems on perfect graphs.
- http://www.cs.concordia.ca/~chvatal/perfect/problems.html

Perfect Graphs
- Conjectures and open problems, maintained at the AIM.
- http://www.aimath.org/WWN/perfectgraph/

Past Open Problems Columns
- By Douglas B. West, from the SIAM Activity Group Newsletter in Discrete Mathematics.
- http://www.math.uiuc.edu/~west/pcol/pcolink.html

Graph Coloring Problems
- Archive for the book "Graph Coloring Problems" by Tommy R. Jensen and Bjarne Toft (Wiley Interscience 1995), dedicated to Paul Erdös. Gives progress and new problems.
- http://www.imada.sdu.dk/Research/Graphcol/

Problems in Topological Graph Theory
- Web text by Dan Archdeacon with a list of open questions in topological graph theory.
- http://www.emba.uvm.edu/~archdeac/newlist/problems.html

Problems in Graph Theory
- Maintained by Peter Cameron.
- http://www.maths.qmw.ac.uk/~pjc/oldprob.html

Problems in Signed, Gain, and Biased Graphs
- Compiled by Thomas Zaslavsky.
- http://www.math.binghamton.edu/zaslav/Bsg/sgbgprobs.html

Three for the Money: The Degree/Diameter Problem
- Students can understand and work on an unsolved problem in mathematics.
- http://www.c3.lanl.gov/mega-math/workbk/graph/grthree.html

Open Problems in Graph Algorithms
- Compiled by Jerry Spinrad.
- http://www.vuse.vanderbilt.edu/~spin/open.html

Unsolved Problems
- Including the list of 50 problems of Bondy and Murty with current status. Compiled by Stephen C. Locke.
- http://www.math.fau.edu/locke/unsolved.htm

Graph Theory Open Problems
- Six problems suitable for undergraduate research projects.
- http://dimacs.rutgers.edu/~hochberg/undopen/graphtheory/graphtheory.html