Nice program!
Here are some feature request from me.

1. Poll
2. Multiple attachments per post.
3. Can attach images and display these images in the post body (with img tags).
4. Excerption: in every sub-forum, the admin user or the owner of the forum can mark some nice topics and other users can just read this chosen topics.

And is it support that assign the role of some users so that they can have permission to maintain selected sub-forum? e.g., the admin can point user A as the owner of forum "ABC" and set the related permissions, the user A have permission to edit/delete/mark topics in forum "ABC" and perform others maintenance operations?