Aside from the usual interface design necessary in such a project I also created default avatar images to be used by forum users and some achievement badges for various accomplishments they earned on the forums:
It was an enjoyable — if long — project to work on. Vanilla’s code is quite volatile and made working on necessary components difficult at times. Because of its volatility we had the necessity to maintain it and look out for bugs right up until the end of my employment at Opera Software.
The Opera Forums may be visited at forums.opera.com.