Servlet development framework for Web applications. LGPL

wingS 3.1 features Swing-like components and utilizes Swing models, Swing events, and a very similar API. A special LayoutManager allows you to place components using designer provided HTML templates. The HTML code generation of the components themself supports PLAF (Pluggable Look and Feel), so it is possible to create a different output, like plain HTML, HTML+CSS, and WML.

Gimp ToolKit. LGPL
GTK+ 2.12.1 is a library for creating graphical user interfaces. It is designed to be small and efficient, but still flexible enough to allow the programmer freedom in the interfaces created. GTK provides some unique features over standard widget libraries.