Stimulating the desire to share

So I've been taking notes for a few weeks on why it is some people are really attracted to share some things, others are attracted to share very little. What is it that stimulates one person clicko n the "share" button on You-Tube or any other social networking site? What prompts someone to forward a useful article? SO the notes I've been taking are around my own behaviour and desire to share. I am wondering how much of this is generalisable to other people and contexts.

1. Relationship building: sometimes I share something because I am aware it is part of continuing a relationship with someone. This can range form the more formal paper I've read that I hope someone else will also find useful, though to something more random like a video clip on You-tube that I thought someone in the family might find amusing. My sharing isn't something planned - it just sort of happens and when I see something I will trigger a "share". This made me think whether "relationship building" is something we consider or design with in mind when developing change programs.
2. Unknown sharing: this is a bit like the blindspot in the Johari window. I realised that I am on many social and business networking sites. It is possible for me to share a message, say on Twitter, and then this is retweeted (forwarded on to others). I have no idea who the people are, though Twitter is useful as it is possible to track the sharing - not so with email. Sometimes the only way I know something has been shared is when I get an email form someone I have never heard of yet they are commenting on something I said. This is a very powerful dynamic at work and I wonder how much this is taken into account when developing communication strategies? I've learnt how random this process is. Got to be in there and involved to have any sense of how the internet can generate both velocity (speed) as well as scaling up of a message.
3. Problem shared is a problem halved: I have found sharing problems and looking for support and answers from others is an important strategy for me. I use LinkedIn to pose questions and also reach out to colleagues. This means I have to describe my problem - this process of sharing usually means I end up part solving the problem as I do the definition! So I wonder whether in our change efforts we spend too much time requiring solutions to be articulated when one strategy may be to help people both find words to their problem as well as find someone to whom they can reach out.
4. Random sharing: ever found yourself telling your life story to someone sitting next to you on the bus and who you only met 30 seconds ago when you sat down?! Well, not quite as extreme, though I have found myself sharing all sorts of things with people which don't fall into relationship building (except perhaps very short term) or as precisely as problem solving. There is something opportunistic here. So I wonder whether we can help more of these opportunistic meeting happen in the workplace?
5. Good idea promotion: yes, I did do some promotion activities, sharing good practices I have seen elsewhere and which may be useful to the person or team I was working with at the time. However, this was only a very small percentage of my "sharing" time. Standing on a stage and telling stories also counts a bit of good practice sharing, though again this was a small part of my sharing activity. So I wonder whether we are over cooking the need to share good ideas?

So what I discovered by my own behaviour is I have not consciously set out the share good practice and good ideas. It is a lot more random than that. Also, my desire to share is really quite complex. OK, I am only a sample size of one - if you have stories about your own desire to share then please write a comment below.

I will be doing some thinking before designing the next communication and "spread" intervention I am involved in.