mbworld:
MBWorld.org Mercedes Benz Enthusiast Community
benzworld:
Mercedes-Benz Forum
benzforum:
Mercedes-Benz Forum
Alas, none are as good as Pelican. I think largely because very few MB owners do as much of their own wrenching on their cars as do Porsche 911 owners. And, of course, no MB model was around anywhere near as long as the air-cooled 911.
All have their share of young arrogant know-it-all a**holes (mbworld.org seems to have a surplus) but some good info can be obtained.