Programming in Logic Languages on the Web (PiLLoW) is a public-domain library for developing Web applications using (constraint) logic programming. It constitutes part of the Ciao Prolog development system. http://www.clip.dia.fi.upm.es/miscdocs/pillow/pillow.html
A concise, example-based introduction to Prolog for people from the humanities. Uses the freely-available Prolog+CG as the example implementation. http://www.huminf.aau.dk/cg/Module_II/10000.html