Three resources I've recently learned of:
1. If you bought a seat of Revit you should be able to get a 708 page Revit User Guide free of charge. Just type in your part number and serial number here. Posted by Damian on AUGI.
2. You can find resolutions to many common problems at Autodesk's Support Knowledge Base.
3. You can also send your wishlist directly to Autodesk here.