At the time of writing, 49 out of our 315 questions are tagged with
reference-request, and at least 10 of these are still unanswered. (We have 20 unanswered questions in total.) In addition, I think that the number of questions tagged reference-request will probably increase. For this reason, I think it's a good idea to create a community wiki that lists resources for answering questions that ask for scientific evidence.
When someone answers a question without citing references, we can refer them to this community wiki.