I discovered The Kneeslider a few years back. It's one of the best private, unaffiliated motorcycle sites to be found on the Web.
One of the coolest things about it is the way they constantly feature very innovative, custom-engineered, handbuilt bikes of all makes. They are very good at doing these as a continuing series that chronicles the builder's triumphs and tribulations along the path to a finished work of mechanical art. For example, they've been following the story of the Musket V-Twin that we posted below.
Two thumbs way up for The Kneeslider.