Hundreds of architects from around the world discuss Revit issues here: www.augi.com
Download "families" (similar to blocks) from this site: www.revitcity.com
Here's a great Revit blog for the advanced user: Revit OpEd
A service for LEED calcs for Revit Models: http://www.greenbuildingstudio.com/About.aspx
I'll add more links in the future.