Solid post (and thanks for the shout-out, too)! I’m with you on the Q&A features. I really think that they are what make LinkedIn really stand out as a social network/forum/blog hybrid that offers real value to its users. I have noticed a jump in more “spammy” behavior lately, but it’s easy to spot and avoid.

One other feature that I think deserves a mention is LinkedIn’s targeted advertising. It’s very inexpensive and easy to set up and identify your targets (ours are users with creative agency experience and interest in web development). Even though it results in less traffic from the ads, I really appreciate how discrete they are visually. Many people don’t even notice that there are ads on LinkeIn. I wrote a bit more detail about the results of using their ad system in a blog post back in January (http://www.newfangled.com/using_linkedin_for_professional_development).

Thanks again for the mention,

Chris Butler