grupal for good

I'm organizing a "barnraising" for a Nashville non-profit in July and I'm soliciting best practices and experience from anyone who's participated in or helped organize a 24 or 48 hour sprint to build a website with a group of volunteers? I've found two Drupalcamps where this happened, so far. Anyone else?

DrupalCamp Paris:
http://civicactions.com/blog/drupaln039go_drupalcamp_paris_a_community_b...

DrupalCamp Florida's case study:
http://drupal.org/node/755498