I mentioned XUL in a previous post. It is an XML-based framework for creating user interfaces. I've also found Adobe Open Source, which contains the products Adam and Eve, which is something similar, i.e. cross-platform libraries for creating GUIs.
So, why do I write about this? I can't use any of these products in the projects I'm working on right now, but I seem to stumble upon them anyway. The thing is that creating the user interface is often a large part of the work when creating an application. Normally, programming the application logic doesn't take very much time compared to implementing the user interface. Therefore, using tools that make it easier to create GUIs is a very good idea. For one, it makes creating GUIs faster and less error prone. Also, if the GUI can be created by a non-programmer, we free up programmer time for other, more demanding (and interesting!) tasks.