UMLet is a lightweight tool for rapidly drawing UML diagrams, with a sound and pop-up-free user interface. UMLet lets you draw diagram sketches quickly, teach UML with a simple user interface, and export diagrams to SVG, JPG, PDF, and LaTeX-friendly EPS. It features a fast, text-based way of editing UML elements.
This release has z-order support, bugfixes, and improved PDF output.
URL: UML Tool for Fast UML Diagrams