My org has an Engineering Guild that I am a "leader" of [in the sense that I just organize calendars and "officiate" the call, it's completely flat otherwise]-the guild itself doesn't make up the company, but rather just exists as a small little "coven" within the larger enterprise, there's about 12 of us, though we don't publish anything out publicly for other teams to emulate. Probably not a bad idea now that you bring it up. We've written code for things that went to local non-profits, and written code that became a fully-funded line of business for the company as a service offering (but wasn't-at the time-part of any scoped or planned work, just an idea one of our SREs had to improve an existing business product, built it, deployed it, showed it to the executives).
What would you like to know?