Social media can't do much without great content or value add. Tools are fine but don't just focus on push technology or your efforts will be Dead On Arrival (DOA)
the importance of delicious, diigo, and "stumble upon" to socialise your finds, your content and your things to help you become visible in google searches. As a result increase your reputation organically! - build networks and links!
looking at the different socialmedia platforms - fab little table (i mean matrix).
But remember - where are your service users hanging out already? - You've got to be where they are to listen and engage in the conversation.