You asked for it (or not), and here it is - a stock exchange for nonprofits, Altruistiq.
If you were about to ask for your own social network, try JustMeans - a linkedin for the public benefit sector.
If you'd like a web portal (remember those?) for blogs, videos, podcasts, news, and research on social change just click over to Change Fan.
Finally, if you'd like an online philanthropy channel, head on over to Philanthropy.TV.