You can find people based on particular expertise which is not necessarily evident from searching profiles when you use LinkedIn Answers.  This Q&A service allows members to pose and respond to questions, and earn "best answer" credits which enhances your brand.  For example, searching for "locum tenens" will find doctors, recruiters and financial people who deal with contract physicians, but it may not say that on their profiles!

Try it at:  http://www.linkedin.com/searchAnswers