UML Diagramming on the iPad
Astah UMLpad is a UML editor specifically designed for use on the Apple iPad. With this free tool, you can create UML class diagrams that include classes, interfaces, notes, text, associations, generalizations, realizations, dependencies, and note anchors. Your models can be exported as a PNG, sent via email, saved into the camera role, or exported into XML that is readable in the Astah Professional desktop software.
The app is simple to use, easy to learn, and a great introduction to the power of Astah.