Types:

• Application-Based State Machine Models
• Event-Driven Model

General

Uni Hannover: Automaten
Schaltwerke

Electronics

AllAboutCircuits.com: Finite State Machines

Programming language

The State Design Pattern vs. State Machine, C++

Scripts

The Power of Finite State Machines: Application and Extension, Flash ActionScript

Wikipedia

Finite-state machine
Event-driven finite-state machine
State diagram
State pattern
UML state machine