Luxor is an open-source XML User Interface Language (XUL) toolkit in Java that lets you build UIs using XML and also includes an ultra light-weight, multi-threaded Web server, a portal engine, and a template engine. It is also Web Start-ready, as everything fits in a jar and requires no loose files.
Rachel is a resource loading toolkit for Java Web Start/JNLP. Rachel offers two solutions that make resource loading for Java Web Start/JNLP apps easy again. Solution 1 installs a URL handler for a new protocol called class:// that delivers content from jars identified by a Java class. Solution 2 embeds a multi-threaded ultra-lightweight Web server in your app that serves up content from jars in the Java Web Start application cache. Rachel also works without Java Web Start, although this might be pointless. Examples and user documentation are provided.