I can't tell from the site, but are these volunteer projects full time endeavors? Or is this something that you commit a couple hours to every other day?
It's usually part time work for social issues. It's focused on the UK at least from what I saw, but there are other opportunities available. Might be revamping some php software or writing something from scratch.
And this might range from consulting on software architecture to systems administration work. I haven't found my combination yet. But there were some pretty interesting things on there.