Stefano, this is one of the better Mac-menu bars I've seen available for karamba. I do have a couple things that I think would greatly improve it though. This may be difficult, I've never made any karamba themes or done much in python, but it would be great if it would work for multiple resolutions. Also, the font does look a little wrong.

The font that you are using is not anywhere near the OS X menu's font (something like lucida grande). I might download it without the font change but I still would prefer a font change

Some ideas for future release would be time in 12 hr instead of 24 hour option. Also, a drop shadow for the menu bar and having the first menu change for whatever program you are working in..like having it say explorer for internet explorer instead of just being a static Finder. I'm sure it's not that easy but if someone can do it, it would sure look nice.

You should really use time.strftime() for the clock, and make the format configurable... e.g. timeFormat = "%a %H:%M %d.%m.%Y" That would be something like Sun 23:50 20.07.2003