This meta question: Resources for answering common questions? was closed some time ago as a duplicate of Resources for Learning Spanish, but it seems to me this question was more about resources for people specifically searching for answers to questions on this site (either to inform themselves before they post, or in answering them itself).
As such I think it is a useful and distinct question worth reopening. I reformatted the sole answer to more explicitly model the "What resources are useful for what type of question" format, and included a number of other resources I though important. If people want to reopen this question, but think such reformatting is a bit extreme, I'll revert it and add it as a separate answer.