Revit Forum Search
As of 5 September 2011, the custom search includes these sites:
For example, let's say you search for 'Slanted Walls' - you would quickly get results from Revit Forum, Revitcity, AUGI and Revit Clinic all in one list. Give it a try!
Let me know if you think there is some other Forum that should be added.
What Revit Wants: Revit Forum Search