Tool for drawing automata and syntax trees

Question

I am searching for a free tool(s) to create visually appealing diagrams of finite automata and syntax trees.
Note: I really just want to draw diagrams. I do not have to create a model or do something fancy with it.

Thanks for your time.

EDIT:
I might add, that I am creating documentation in Latex and therefore I am also open to tex-based diagramming solutions.

Answer 1

Does Graphviz meet your needs: creates diagrams from text example: http://www.graphviz.org/Gallery/directed/fsm.html