The GXT themes which come by default are ok but they're all essentially versions of the same thing with different colors. Looking around I can't find any attractive commercial or free themes.
Is there a good place to find new themes or has a third party market failed to emerge so far?
Currently a set themes for GWT really very small. There are several ways to solve this problem: First, you can use additional libraries, such as SmartGWT or ExtGWT, which provide a list of components and their own set of skins. The second way is to override the styles of GWT-components in your CSS file. In my projects, I use both of these approaches. Using the library, I expand the list of available components, and changing styles with the help of CSS-file, which override the GWT-component classes and Ids.