Hi Yassine,
Are you aware of the work we did on Moose and Mondrian? The former provide a meta model, and the latter a powerful visualization engine. UML is one of the visualization we can do.
There is a screenshot of the browser I use on a daily basis: http://bergel.eu/screen-capture.png
David R. extended the OB browser with alternative ways to visualize code.
By the way, we're in Lille, we could meet up...
Cheers, Alexandre