LinkedIn has launched LinkedIn Answers today, a service similar to Yahoo Answers that lets you ask questions to members of your network. It should be noted that Google has recently closed down its Google Answers platform due to less activity and unacceptability by mass.
If successful, Linkedin can increase activity on the site. You enter your question, pick the members of your network who are likely to know the answer and receive answers from your connections, their connections, and experts who use LinkedIn. You can browse the questions by category and gain expertise points every time the question asker picks your answer as the best one. The top experts then appear in a ranked list. Unsurprisingly, most of the questions are currently about finding referrals and connections.