TL;DR: Besides Ask Patents, CS50, Math Overflow, Meta Stack Exchange, and Stack Apps, what open communities that use the Stack Exchange software have non-standard features or use standard features in a unique non-standard way?
By Stack Exchange software, I mean the software that powers Ask Patents, CS50, Math Overflow and Meta Stack Exchange. Regarding the scope of this question, please consider Stack Overflow for Teams as different software.
This question came out while thinking about the current situation of some Stack Exchange Network sites that might take advantage of stuff found in the mentioned sites and other sites that use the same software.
As I understand, the Stack Exchange network was created after the success of the questions and answers community for programmers; Stack Overflow launched in 2008, then there was the "Trilogy" (Stack Overflow, Server Fault, Super User, and the first Meta) named after the Star Wars movies existing at that time. There was the possibility that people created their Q&A site using the same software, known as Stack Exchange 1.0. In 2010 a new process for Q&A site creation based on the "Trilogy" model was launched, requiring people to make a site proposal in Area 51, known as Stack Exchange 2.0.
Some sites use non-standard features or standard features in a non-standard way. By "non-standard way" I mean beyond what the Community Managers can tweak without requiring the intervention of a developer and beyond the recently defined process, like how to make a feature request to customize the Ask Question form.
So far, I have identified Math Overflow, Ask Patents, and Stack Apps.
Are there other sites that have non-standard features or use standard features in a unique non-standard way?