Recently, my "what are you working on" mentioned a suggestion to lawyers that connecting directly best enables LinkedIn legal client referrals.
A survey of the questions in the law and legal question and answer section will find many members seeking legal services right on LinkedIn, and simply asking something like "hey who knows a Shark Attack Business Lawyer in Boston?"
If another member knows such a lawyer, they can answer the question and by using your direct connection - provide a direct link on the answer to your LinkedIn profile.
2's and 3's just aren't in reach of the LinkedIn webpage used to answer questions and suggest experts.