1. Implementing more BBCodes (Ex embed spoilers, more media, heading, colored text.
2. Profile Customization (Ex About Me Page, Social Media Links)
3. Quoting Posts from other users and notifying them someone responded to their posts by quoting them.
4. Tagging other users using @
5. Forum Signatures
6. A Special Member Title for Contributors (Donators) (I seen this in many forums as a thank you gift for donating).
7. Forum Badges (A just fun way to show your achievements in the forum).
8. A New Captcha system (preferably the one click captcha)

I've been in many forums, So I thought it would be nice to suggest these to you all. 

Badges denoting leadership i.e. debutant. signatures would be nice too.