Few feature requests:-
1. On the categories page, it will be very elegant if we can display icons of most active users, recent questions/answers against each category.
2. On the main menu "Ask A question" can be shortened to "Ask". or even better as a button with just Ask written on it.
3. Infinite scroll
There are some more in my mind, if you think what I am talking makes sense than PM me and we can talk.