PROLOG COMPILERS
Free Prolog Compilers:
Strawberry Prolog (Light edition) www.dobrev.com
Beta-Prolog: www.idiom.com/free-compilers/TOOL/Prolog-10.html
ECLiPSe Prolog: eclipse.crosscoreop.com
IC-Prolog II: www.cacs.louisiana.edu/~mgr/404/burks/foldoc/38/55.htm
PD Prolog: www.cs.cmu.edu/afs/cs/project/ai-repository/ai/lang/prolog/impl/prolog/adapdpro/0.html
Commercial Prolog Compilers
Strawberry Prolog (Middle and Professional editions) www.dobrev.com
ALS prolog: www.als.com
Amzi Prolog: www.amzi.com
Arity Prolog: www.arity.com
LPA Prolog: www.lpa.co.uk
SICStus Prolog: www.sics.se/sicstus.html
Quintus Prolog: www.sics.se/quintus
For more detailed list look at Logic Programming Archive at Oxford Comlab