LinkedIn Strategy: Optimize Your Profile is a great course in Pluralsight by Jason Alba that covers a lot of ways in which you can make your LinkedIn profile more effective – and also some suggestions on how to improve your networking in the site.
There is plenty covered, starting with your picture, professional headline, summary and going into how to use rich media, how to get (and give) recommendations and more.
A particularly interesting tidbit is how to re-use recommendation lines on your summary, experiences, sites and more.
Overall, I found the course to be very useful and full of interesting techniques and suggestions. I think that if you use his ideas on your profile, it will be much better and more useful. I definitely need to spend some more time on mine.
Recommended, specially if you already have a Pluralsight subscription.