"The brainchild of Plogue Art et Technologie, Bidule is a cross-platform application that is gaining recognition world-wide as the new standard in modular music software" - www.plogue.com
This tool is not free but is currently only $75 US. At first it seemed very promising, same paradigm as Buzz but more evolved. However, I installed it on my Windows XP machine at home and again at work on my XP-64 machine and the interface seems kind of buggy. Clicking the "Start" button shifts the whole workspace and moves some modules off-window, with no way to retrieve them. Very frustrating. Hopefully they'll work out some of these quirks as I'd really like to try it out.