I use LinkedIn, especially for coaching recommendations. I don’t know if it helps me get more clients, but I keep thinking it should 🙂
Just remember, a recommendation is not a reference. A recommendation does not address any specific concerns you might have about a potential candidate (or a potential employer). A recommendation is just that: data that one person liked something about another person.
So use them, but don’t rely on them for references. After all, how can you tell if what one person liked is something you would like?