Have the sub forums show on the main board like discourse has. As an option.
Main forum title
sub forum 1, sub forum 2, etc
A feature that automatically sends a reminder email to users who haven't visited the forum for certain time would be very helpful.
Additionally, on Admin Control Panel in "User Search" section... it would be great to pick more than two features, such as both INACTIVE people and those have VALIDATED emails etc. Right now, you can only pick 1 option.