Today I found MO questions where commenters recommended that Proof Assistants or History of Science and Mathematics would be preferable to MO. Other better placements I remember include Mathematica, Theoretical Computer Science, and Mathematics Educators.

I can understand not wanting to make a very long list of suggested alternative SE sites, but are the listed options reconsidered on a regular basis and updated accordingly? And what is the best approach to suggesting a site that isn't listed?