LinkedIn is a professional network built around one's employment capabilities. It is often referred to (I believe somewhat incorrectly) as an online version of your CV or resume. People (e.g., Christopher S. Penn) who use LinkedIn expertly will be the first to say that this service is sorely underrated as a place to develop business, grow your capabilities, and promote your projects and opportunities. Here are some thoughts on amping up your LinkedIn presence.
The first horror show I see when reading other people's LinkedIn profiles is that the writing is completely dry, as if robots are the only ones who will read them. Though you should write with robots in mind, this is still a human network, so write as if you want someone to actually read your profile. Here's the first paragraph of my summary:
I show businesses how to use social media technologies for external community building and outreach, and for internal collaboration. I have over 10 years experience with social media and 16 years experience in enterprise computing environments. I blend emerging tech knowledge with enterprise culture understanding.
You can tell what I do; you have a sense of what I'm hoping you want from me; you get a hint at my unique value proposition to businesses on this regard. It's not the best paragraph ever written, but it's definitely clear in explaining my core interests.
Make your summary explain, succinctly, why someone would want ...