I've noticed when a question is re-pushed to the top of the question stack (and thereby making it onto the home page of Stack Overflow) it can be tricky to figure out exactly what about that question (or one of its answers) has changed to warrant its re-push. It would be great if alongside "oldest", "newest", and "votes" answers could be sorted by "active", those that have had comments added, edits made, etc., going to the top of the pile. That way (for example) active threads of discussion about particular answers can receive fresh attention.