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 Geometry: 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.
