FolioVision

Features:
<ul>
<li>Guest posting – any forum posts posted with a known email address get associated to the WP user, any posts with a new email address get a new user account. Enable in Tools -> FV BBPress Tweaks.</li>
<li>Forum moderation – any new forum posts or topics get into moderation. Only admins and the original posters can see the pending posts. Enable in Settings -> FV bbPress Tweaks.</li>
<li>Nicer permalinks – get rid of /support/topic/{topic-slug} /support/forum/{forum-name} and start using hierarchical /support/{forum-name}/{sub-forum-name}/{topic-slug} structure!</li>
</ul>
Known bugs:
<ul>
<li>You can open the topic editing from front-end for pending topics</li>
<li>When you delete a reply, the pending replies no longer appear, just open the topic again with its original URL</li>
</ul>

FV bbPress Tweaks

Adds moderation and pretty URL structure to your bbPress forums.

Silkalns

WP Chill

Cristian Raiber

A very useful plugin for everyone using WordPress. Adds reCaptcha security to the WordPress login form, register form and comment form. This plugin could help your blog get rid of a lot of spam comments or brute-force attacks.
Nothing gets passed it if the reCaptcha doesn’t validate.
A few notes about the plugin:
<ul>
<li>Supports audio or image captcha types</li>
<li>Can generate the reCaptcha image / audio type in a number of predefined languages</li>
<li>Adds reCaptcha protection to the WordPress login form</li>
<li>Adds reCaptcha protection to the WordPress register form</li>
<li>Adds reCaptcha protection to the WordPress comment form</li>
<li>Adds reCaptcha protection to the WordPress recover password form</li>
</ul>

Uber reCaptcha

This plugin adds the reCaptcha form to the WordPress login form, recover password form, register form and comment form.

FV bbPress Tweaks vs Uber reCaptcha