http://www.cs.kun.nl/~freek/digimath/
Theorem provers (!) - marked are particularly useful with Prolog.
http://www.prover.com/
http://pvs.csl.sri.com/
http://www.telelogic.com/
http://www.cl.cam.ac.uk/Research/HVG/Isabelle/
http://www-verimag.imag.fr//TEMPORISE/kronos/index-english.html
http://www.lemma-one.com/ProofPower/index/index.html
http://ls4-www.informatik.uni-dortmund.de/RVS/P-TLA/
http://www-verimag.imag.fr//VERIF/methodes-english.html
http://www.cs.cmu.edu/~modelcheck/smv.html
http://i12www.ira.uka.de/leantap/
(!)
http://wwwtios.cs.utwente.nl/lotos/#tools
http://www.cs.utexas.edu/users/moore/acl2/
http://www.dat.ruc.dk/software/index.htm
(!)