Scalable 2D Vector Graphics API
SVG API (JSR 226) is a great extension to Java ME that allows to develop the User Interface of the application in a more powerful way, using an SVG document. This API supports SVG Profile SVG Tiny, version 1.1.
With SVG you can design the user interface in any design software, like the ones from Adobe and place them inside the mobile screen using Java ME. SVG files are automatically scaled to the phone screen and can have hotspots areas where the user can browse and fires an event that can be captured by a Midlet.
A great doc titled MIDP: Scalable 2D Vector Graphics API Developer's Guide about this API is available on Nokia Developer.