I always enjoy reading Guy Kawasaki's weblog, and with his latest post he offers some great advice on making the most of your LinkedIn profile:
Ten Ways to Use LinkedIn : http://blog.guykawasaki.com/2007/01/ten_ways_to_use.html
What can I say, I'm hooked on this service. Are the days of bogus claims on CVs/resumes behind us?
Updated 2021 : note that the above post is out-of-date, given this post was originally published in 2007, but is left here for archival purposes. I have unlinked the original external link as it is now dead, Guy's home page is now here: https://guykawasaki.com/