The new USAService.org website is a fine idea, but it's missing solving the real problem. There are already a ton of websites with volunteer opportunities (look at http://www.usaservice.org/page/content/opportunities/ to get a sample
of the number of them) - the real problem is that if you wanted to volunteer, you might have to spend a bunch of time searching all those websites, and you'd give up after awhile. That's the problem that needs to be solved.

If all those websites would share their information with each other, then a search on any one of them would let you find the relevant results from all of them.

This is not far-fetched, this can easily be done using existing standards (similar to RSS). What needs to happen is for a large number of these websites to adopt this model, and cooperate. This idea is my answer to the call to service: I'm promoting this idea that we don't need more websites; we need the websites to share information about service opportunities.