[jeffmould]

Not sure where you are located, but I know that the Washington Post lists volunteer opportunities in the job ads online. Most of the time there are developer opportunities on there for non-profits looking for help with websites or other projects. I know a few people that have used those opportunities to give back and also build/refresh their personal portfolios. If you aren't in the DC area, you may try other newspapers of similar size. I am only familiar with the Post though.