Hung, T. and Rodger, S. H. Increasing Visualization and Interaction in the Automata Theory Course. In Proceedings of the 31st ACM SIGCSE Technical Symposium on Computer Science Education (SIGCSE 2000), Austin, TX (2000), ACM Press, New York, pp. 6-10.
From the JFLAP website:
"JFLAP is software for experimenting with formal languages topics including nondeterministic finite automata, nondeterministic pushdown automata, multi-tape Turing machines, several types of grammars, parsing, and L-systems. In addition to constructing and testing examples for these, JFLAP allows one to experiment with construction proofs from one form to another, such as converting an NFA to a DFA to a minimal state DFA to a regular expression or regular grammar."
JFLAP has undergone continuous development for a number of years. It is an active project, about to bring out its sixth release.