Automata and Formal Languages: A terse statement of important definitions and theorems in this field of study.
Automata and Games Theories: Key concepts and principles, major contributors, references.
Automata Theory: An essay by David Weir.
Automata Theory: Wikipedia article on finite state machines with links to articles about pushdown automata, linear bounded automata and Turing machines.
Computation, Automata, Languages: Notes, small essays, explanations, reading lists. By Cosma Rohilla Shalizi.
Finite State Machine: Wikipedia article on FSA, Moore and Mealy machines.
Turing Machines: A brief survey of finite state automata, pushdown automata, linear bounded automata and Turing machines.