Don't you just hate it when you think you have a good idea and Google tells you there have been quite a number of people that already had the idea a long time ago...
When I was recently pondering the usefulness of models the thought occured to me that it would be not so difficult to generate a model repository from Java source code in a manner like JavaDoc but more advanced or enhanced. This idea as I suggested and expected was realised by others such as Compuware's JavaDoc enhanced with UML models.
Taking it one step further; all roudtrip UML-Java tools offer even more.
An interesting fact of course and completely in line with current development in MDA/code generation tools, ok, I never said it was a revolutionary idea ;-)