An interesting development where web technologies meet real societal needs is the rapidly growing phenomenon ofcommunity lending. Microcredit has been around for longer as a concept to empower poor people and communities by letting them help themselves by creating social systems to provide small loans. These systems help create the trust, do the administration, etc. With the web, however, new socio-technical dimensions are added to the idea. For example, small loans can become global instead of just local in scope, much more background information on debtors can be provided, risks can be reduced by automatically distributing a loan over many lenders and so on.
Some links:
Making CommunitySense 