Complex sentence: What makes this fan site unique is the mutual working relationship between the crew of TheOneRing.net and that of the Lord of the Rings movies, and now The Hobbit, that enables the site to bring its readers exclusive news from the set.
Split into simpler sentences: What makes this fan site unique is the mutual working relationship between the crew of TheOneRing.net and that of the "Lord of the Rings" movies, and now "The Hobbit". This relationship enables the site to bring its readers exclusive news from the set.