onigoetz

This plugin allows to use the password from a working phpBB installation to log into a WordPress blog. or on the other side to log into phpBB with the WordPress user.
The username for the administration must be the same on the two installations. 
Otherwise you will end having admins that have no privileges on the other part.
<h4>How it works</h4>
There is no actual “sync” of the users.
When the app is configured correctly. the app checks that the user who tries to log in is at least registered in one of the systems, if yes, and the password is correct : he’s logged on both systems and his account is created if missing. 
On password change it should also set the password on both platforms.
<h4>WP2BB</h4>
With WP2BB, you can now define that your posts are published in a forum, so that your community can add comments directly on them.
You can add the method “wp2bb()” on your template so that you have links to your forum to add comments and a replies count
There is also a widget to list the last replies in the forums
P.S. : WP2BB was created by Alfredo de Hoces (http://www.alfredodehoces.com/)
<h3>Uninstall</h3>
To uninstall, you have a few steps to make
Go the the Plugin options, revert the “auth mode” to “DB” and not “wpbb” 
If it doesn’t work go to the ACP in General -> Client communication -> Authentication
Then go to the wordpress control panel and disable the plugin.
The last step is then to go with FTP in the PHPBB folder and rename the file “common.php” to “common.wp.php” and the file “common-orig.php” to “common.php”.
Your configurations should be separated again

PHPBB Single Sign On

Authenticate in Wordpress and phpBB at the same time

Orson Teodoro

This plugin is under heavy development. Please do not use it in production unless your willing to accept difficulty of 
upgrading or correctness of the conversion.
ForumConverter migrates post, topics, and users from one forum to a WordPress compatible forum. Currently, 
ForumConverter supports phpBB 3.0.9 to bbPress 2.0 conversion in addition to migrating users as subscribers 
to your WordPress blog.
ForumConverter migrates users from the source forum database to WordPress compatible forum so that migraters can take 
advantage of BuddyPress social networking. This is not a bridge.
For phpBB-to-bbPress conversions, ForumConverter is capable of…
<ul>
<li>reproducing the same forum tree structure for bbPress</li>
<li>reproducing forum post using the same same user, timestamps, sticky flag</li>
<li>allowing converted users to sign on using their existing phpBB password.</li>
<li>converting between BBCode or native bbPress HTML markup</li>
<li>supporting inline attachment conversion and whole topic/reply attachment conversion.</li>
<li>migrating of instant messenger info, global moderator membership, and emails.</li>
<li>password protected forums migration using the same phpBB password</li>
</ul>
Some things that are impossible to do for ForumConverter for phpBB-to-bbPress conversions
<ul>
<li>Complete conversion of custom BBCode. Only YouTube BBCode is supported but BBCode lite does not support YouTube tags. </li>
</ul>
Please read the installation instructions before preceeding. Remote conversion is not supported.

ForumConverter

Migrates a phpBB forum into a bbPress forum.

PHPBB Single Sign On vs ForumConverter