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A C-like language interpreter with C++-like classes. By SoftIntegration.
http://www.softintegration.com/products/BFC Automata 
An interpretter for different types of Automata, including a simmulation of Turing Machines. [Freeware]
http://automata.borfig.com/
Andreas Kupries: Compiled and Interpreted languages 
Treats the meaning of interpretation, with definitions.
http://www.oche.de/~akupries/ics_lang.html