Thanks for the detailed and thoughtful response. The subject of social capital is new to me (as is the phenomenon of mailing lists!) though I am familiar with the term "intellectual capital" and assume there is something similar. But I agree it would be worth building and hence I will try to help in any way I can.
For starters I would point out that in your post you seemed to emphasise "process", that it is not easy, no fool proof ways, not visible etc and then suddenly popped the issue of "content" viz negative social capital! Also, is social capital tied in some way to our (competing!) concepts of "Goa" to which you alluded at the start of your post? So we seem to have both a squishy content and a squishy process on our hands! I guess it makes for "interesting times" in the Chinese sense. Regarding the eyeballs built up over the years, it would be interesting to have some figures about this (aside from the word that there are 7000-plus goanetters out there). What we probably want to focus on the "fingers" which take the trouble to post on goanet (assuming one finger typing like mine!), whether they are increasing or decreasing each month, how many are new to goanet etc. Finally, pls call me Phil as "prof" makes me uncomfortable!