Some new features we may want in forums:
- more caching to improve performance
- consider the DB schema to see if we might need different indexes to speed it up
- let people subscribe to a topic, or a whole forum. This would email them every time someone posts a new message. Instead of emailing the new message to them, you should probably tell them to visit your site to read the new posting. This ensures that you get the proper credit in your "hits" for advertising revenue, and it also lets the user view the message in the proper context so they can post a reply.
- let users upload an avatar image. Make sure it's small enough, and save it as a blob in the DB.
- Have some kind of ranking system to identify users who post a lot of messages
- Add a search function
- Let people send each other messages in a private forum - this way they can share private messages without knowing each other's email address. The next time a person logs in, it could check to see if there's any private messages waiting, and it can bring you to that forum if it finds a new private message.
Of course, other users can't read those messages - you have to be in the "from" or "to" in order to read a message in the private area.
Here's an example of an open-source Forum package that does these functions, and a lot more. This might help to give people ideas of what they want to do: