Foreword: Well I made this originally for subscribers of mybbforums.com, but that fell apart and I've gotten several requests for this plugin since then, so I've decided to just update it and release it to the MyBB community for free! 
What it does: This plugin will allow board admins to specify certain forums that require all new threads to have a prefix attached to them. Very simple, very straightforward, very easy to use. The .zip file includes a readme that will tell you how to install it just in case.
Comments/Support: Any support questions can be asked and will be answered in this thread, and please report any problems you find here as well. If you've got a comment/suggestion for the plugin I'd be happy to hear it, just post it here as well. I'll be checking in occasionally.
Current Version: 1.1
Link: http://mods.mybb.com/view/require-thread-prefixes
Donate
Feel free to donate so that I can keep on making and updating these plugins for MyBB! Click here to donate, any little bit helps
!
Enjoy and feel free to +rep me if you like it!!! ~fizz
What it does: This plugin will allow board admins to specify certain forums that require all new threads to have a prefix attached to them. Very simple, very straightforward, very easy to use. The .zip file includes a readme that will tell you how to install it just in case.
Comments/Support: Any support questions can be asked and will be answered in this thread, and please report any problems you find here as well. If you've got a comment/suggestion for the plugin I'd be happy to hear it, just post it here as well. I'll be checking in occasionally.
Current Version: 1.1
Link: http://mods.mybb.com/view/require-thread-prefixes
Donate
Feel free to donate so that I can keep on making and updating these plugins for MyBB! Click here to donate, any little bit helps
!Enjoy and feel free to +rep me if you like it!!! ~fizz