Here are some screenshots of JForum. Click on the images to see a larger version.

Main forum page, listing all categories and forums available to the user, as well information about the last message of each forum	Topic listing page, showing the first page of topics of some forum	Posting a new message. Note the text formating options and the "Attach Files" button
Reading a topic	Board configuration options in the Administration Panel	Listing of registered members
Attaching files to the message	Message displaying the File Download box of an attached file	Information about current online users