This is a great resource! Kudos to Mark! You can meet him and other nonprofit WordPress people in the "Community of Practice: WordPress" space on NTEN's website (Nonprofit Technology Network)
The membership is free, just need to register.

Also for nonprofts coming to the Nonprofit Technology Conference in San Jose, you can experience a full day WordPress Day - Check it out.

Disclosure: I am a member of NTEN and I will be speaking at the conference and also session proposal to WordPress Day. Follow me on Twitter @bph