1. Search Suggestions
2. Questions (Search for Title and Filter by Time (Days, Week, Month, Year)
Rational : As time passes, Answers to very old questions becomes untrue.
Ability to search for questions by a keyword and filter by time can allow a user to
to have a fair idea about a topic over a period of time. This will also allow site owners to edit old questions with new correct answers. It is a way of watching a topic evolve in a community. It will also allow webmasters to study trends on topic and how they evolve in their community. I don't know if there is QnA software that already implements this feature.