I would suggest that, if you ever introduce blog type article pages that they will be of more use there. People are generally less likely to share conversations where they are actively engaged in a community than an article which provides a composed insight.
Have you thought about social bookmarking aggregators, such as ShareThis or AddThis?
Another consideration might be a dedicated social page including Twitter feeds, Facebook page feeds and (not available yet) Google+ feeds as well as links to those social properties. Google+ launched "Business Pages" about two weeks ago in the same vein as Facebook pages. If executed well (not much effort required) then these can be huge traffic drivers. Google+ has been growing steadily since it's launch, to the point that Facebook have taken quite a lot of notice. they do have a long way to go but as Google continue to integrate their huge range of services and with Google Music and other services on the way there are undoubtably opportunities to be taken advantage of by stealing a march.
I've often wondered how I could best contribute to this site outside of the donations and being an active member of the community and social is something that I would gladly assist with, should you want to pursue this area of site promotion.