AndyUML is a new tool for Android that allows you to draw UML diagrams in your Android mobile device. AndyUML relies on the yUML service to render the diagrams. Basically, with AndyUML you can write and store the textual UML definitions to be sent to yUML for its visualization.
Of course, this is a drawing tool and not a modeling one but useful nonetheless.
Another tool to add to the small but growing list of UML tools for cell phones, ipad and similars.