You have to be careful on LinkedIn and you can't cold call people. You can though find the decision makers, connect with them and build a relationship. Many of my best clients took me meeting them 5 to 7 times at events or through string of emails. I try early to connect with them on LinkedIn, when they see my profile, it gives me more credibility and makes it easier to set a meeting to discuss IM.
I just started a LinkedIn Group (link below) and am going to use this to get new clients and other marketers I could outsource work too. Let me know your thoughts on using LinkedIn this way.
Internet and Social Media Marketing For Retail Business | LinkedIn