Group permissions determine what type can be used, along with what code such as BBC, HTML, or PHP. An example of default restrictions would be Page & PHP is allowed by the admin only.
If your wondering what "file" type is, then it's nothing more than taking a post with an attachment and display to look like a item download page. All the information is there, it's just a manner of how to display it.
It would also make it easier to make an add-on for it. Someone might want a custom "reviews" add-on, that mainly just displays the information within the post to look like a review page.
All content of any type can all be found within the forum. No need for separate sections. Although if someone wanted it a separate section, then they could use a custom mod.
2.| Major: option to make any age, gender, or custom profile field into a Group, so that it can be given permissions. This would allow sites to restrict content by age, gender, or custom profile field. This is something I have not seen any software do, but is always asked for as a mod/add-on.
3.| Major: options to manage blocks of content in sections around the forum. One for the top, right, bottom, and left. Not just one side bar. The only blocks that should there by default would be the ones currently in the sidebar, along with a custom block option that can output PHP, HTML, or BBC.
There should be a manager to install/remove these blocks of content. These blocks should have certain options such as: who can view them and where they can be viewed(allow multiple areas).
4.| Minor: option to apply a style to a category, and all boards within can inherit. This makes changing a style for multiple boards easier. Already implemented...
5.| Minor: I think that "Discussions" & "Messages" should be changed to "Topics" & "Comments".