At the top of the site tour, it currently says:
Sustainable Living Stack Exchange is a question and answer site for folks dedicated to a lifestyle that can be maintained indefinitely without depleting available resources. It's built and run by you as part of the Stack Exchange network of Q&A sites. With your help, we're working together to build a library of detailed answers to every question about sustainable living.
What do you think? Any suggestions for improvements.
They typically follow quite a specific recipe:
{site name} is a question and answer site for {the site's primary audience}. It's built and run by you as part of the Stack Exchange network of Q&A sites. With your help, we're working together to build a library of detailed answers to every question about {site subject}.