Now here is a glimpse at what we are using uDig for. I think all the digging in the internals of several Open Source projects is now beginning to pay off.
The Anaconda Workbench is an application for viewing and testing car navigation databases in the forthcoming Navigation Data Standard format (NDS). (This is a closed source project of Harman/Becker, so I cannot offer more than some general information here.)
We implemented a Geotools extension for the NDS format, and a corresponding uDig catalog plug-in. This was enough to build an NDS map viewer. The map has multiple levels of detail in separate layers. We use SLD for styling the layers and for activating the appropriate layer depending on the current map scale.
On top of the map viewer functionality, there is a name browser which allows you to select road names and display the road on the map or use it as a start or destination for a route.
There is also a route calculator plug-in which finds the shortest route between two points and highlights the route in a separate layer.
More functionality will be added step by step. In the end, the Anaconda Workbench shall become a front-end for our map compilation process and not just a viewer for the compiled map databases.