These have probably been mentioned already, but I would love to see the following abilities added to the IPB.
General
1. Ability to dictate which user group could highlight their topics area.
Approved User creates a topic and the entire area is highlighted Topic Title > Replies > Starter, etc.
2. Ability to set user(s) to show Signatures once per topic page.

Security
1. Ban User(s) from Select Forum(s)
2. Easier banniong system where the admin or approved group could ban from the user(s) profile card.
3. Option to force user(s) to require birth date and location upon registration without using coppa.

I like Security #1