Just tripped across an interesting column about social networking spam or, perhaps more accurately, how one can use social networking systems more effectively without spamming everyone whose email address has ever crossed your transom. The salient bit:
The first thing you have to do is get the right frame of mind about why you’re using technology to help you manage your relationships. It is not so you can pretend to a larger number of people that you care about them when you really don’t. It’s so you can treat more people who you really do care about as you would like to treat them, if only your brain were capable.
ObReferences to Dunbar’s Number, etc.