I've always loved the default MyBB theme. Personally, I think it looks much better than PHPBB's default theme. Since MyBB is GPL, I've often thought about porting it over for use with Advanced Forum 2.x. Last night, I spent a couple hours and got pretty far. It still has some rough edges but it's not bad. I can't really spend any more time on it right now so I decided to put what I have up here in my blog both to show what I have so far and share it in case someone wants to finish it off.
If anyone polishes this up and uses this on their site, I'd be interested in seeing it. I got it probably 80% there and but all know the last 20% can be a killer. ;)
In the attachments below are screenshots as well as a zip of the style.