In testing my source level Java to D converter, I tested it by converting a subset of the Java Collections API, specifically HashMap and its dependencies. The result is dj. If there is interest, I will do more. If not, this was just a test anyway :)
After you have downloaded and unzipped it, you will find a few files. To build it, just type 'make -f win32.make'. This will build a file named dj.exe in the obj/ subdirectory. If you run it, it will test the implementations.
As a special surprise, I have also included a port of Doug Lea's ConcurrentHashMap.
If you would like to contribute, there are a few things that need to be done to what is already there, such as documentation, a Linux makefile, better tests, and even making them into templates.