A tool for simulating, visualizing and transforming finite state automata and Turing Machines.

Visual Automata Simulator
Free
Offline
http://www.cs.usfca.edu/~jbovet/

Creates, simulates and transforms DFA and NFA machines
Creates and simulates TM
Batch tests for TM: useful features to test a bunch of files quickly!
Easy-to-use GUI interface (multi-documents)
Smart links between objects
Machines can be drawn using the mouse - and resized at any time
Multiple machines can be created in a single document
Multiple documents can be opened at the same time
Documents can be saved and reloaded from disk
Debug mode to see exactly how the machine is working (each step has a different color)