How the web can transform philanthropy

I was just selected as runner-up for Tactical Philanthropy's one post challenge and despite my competitive nature I couldn't be happier to come in second. Did I suddenly have an awakening and discover that winning isn't everything? Of course not! My sudden comfort with second best is because the winner of the one post challenge was able to harness the power of viral marketing and received 683 comments for their blog posting compared to my 15 comments. The run away success of their post got me thinking about the power of web based networks to do good in our communities. So what nonprofits do you think do a good job harnessing the power of the internet to connect people to causes?