Based on the comments, some progress has been made in the following questions. In many cases, people have indicated that they know the answer, and/or people have encouraged some of the commenters to turn their comments into answers.

In such cases, one thing you can do to help is to further encourage people to write answers, or even write an answer yourself if you think you can, after so much progress was made in the comment chain (which might help you to write an answer).

The list is presented in an answer to this post, in Community Wiki format so that users can edit it if they find more such questions, or they can strike items off the list if the question does become answered.