[FreeGeek](http://www.freegeek.org/) on [SE 10th & Market](http://maps.google.com/maps?f=q&hl=en&q=1731+se+10th+ave,+portland,+or&ll=45.510521,-122.655838&spn=0.00509,0.014849) is a voluntary organization dedicated to reduce waste and encourage reuse and recycling of computers. They run an adoption program that allows anyone to volunteer in the recycling facility and earn a computer in exchange 24 hours work. Alternatively, you can volunteer for the "build" program and learn everything you always wanted to know about PC construction.
Personally, I have just started to volunteer with the systems administration group maintaining the networks, mailing lists etc. used by both FreeGeek and the local organizations they support. It's all Linux based, open source software, so I feel right at home :-) My first contributions have been working on traffic shaping on the firewall and creating a [Google sitemap for the mail archive](/computing/linux/google-sitemaps-for-pipermail-archives).