Open Problems
Collected by Jeff Erickson. Mainly in geometry.
Open Problems from the Geometry Junkyard
Compiled by David Eppstein of the University of California at Irvine.
Open Problems on Discrete and Computational Geomet
Compiled by Jorge Urrutia, University of Ottawa.
Steiner Trees
Open Problems with Steiner Trees, maintained by Joe Ganley.
The Open Problems Project
A project to record open problems of interest to researchers in computational geometry and related fields.