Deductive Database with Datalog, SQL, RA, TRC, DRC
Syntax tree editor for rapid annotation of existing text
Euler Yet another proof Engine
Syllog is a system for teaching logic, with anonymous answer logging
C#Prolog -- A Prolog interpreter written in managed C#
Java Internet Prolog (Moved to GitHub)
TuCSoN tuple-based coordination middleware
Teaching planner tool to help universities in developing countries
Constraint Logic can solve word logic puzzles.