Stefano Lissa

Injecting ads inside the bbPress generated pages has never been so easy!
You can add whatever JavaScript and HTML code you want on top and bottom of each page and between topic and reply lists.
Interleaving ads between replies if the best way to monetize your forum.
Adding custom messages on page footer, you can easily invite user to sign up to participate the discussion. 
Or, using a shortcode, display a sign up/sign in box (there are plugins that provide those kind of forms).
And why not briefing the forum rules just before the new topic or new reply forms?
Injection points:
<ul>
<li>before and after the single forum page where all topics are listed</li>
<li>before and after the single topic page where all replies are listed</li>
<li>before the new topic and the new reply form (pretty useful to give evidence to your forum rules)</li>
<li>between the topics and the replies blocks (perfect to inject advertisement)</li>
<li>just before and after the single reply text (maybe not very useful)</li>
</ul>
<h4>Test mode</h4>
In test mode the administrator can surf the forum and find out all injection areas and then configure them from the setting panel. Cannot be easier than that.
<h4>Syntax highlight</h4>
Using Code Mirror as editor, you have the syntax highlight for your JavaScript, HTML and PHP which makes it easy to edit and check the code. 
There is even the autocompletion for some tags!
<h4>Support</h4>
Tips and tricks can be found on the [http://www.satollo.net/plugins/ads-bbpress](Ads for bbPress page).
For ideas and support use the <a href="forum" rel="nofollow ugc">https://wordpress.org/support/plugin/ads-bbpress</a>. It’s a free 
plugin made in spare time, be patience.
<h4>Design Help</h4>
A designer available, for free, to create a logo for this plugin to be used in this page? 
And maybe the top banner?
Thank you!
<h4>Translation Help</h4>
Contribution to the admin side translation <a href="here" rel="nofollow ugc">https://translate.wordpress.org/projects/wp-plugins/ads-bbpress</a> 
(will be downloaded automatically by WordPress, great feature!).

Ads for bbPress

Injects ads code (and more) on bbPress pages (top, bottom and between topics and replies)

Luiji

This widget provides a nice, optionally thumbnailed list of Zazzle products 
based on query parameters you configure it with, including the store, search 
terms and sorting mechanism. Unlike other Zazzle widgets, this one only uses 
the referral identifier that you give it, or none at all if you do not 
specify one (you know who you are — wink).
Additionally, this widget can be embedded into your posts and pages with a 
shortcode. These shortcodes look something like <code>[pizazz query=asparagus rows=8 
columns=3]</code>.
I use PCRE to parse the RSS feeds. If Pizazz does not work, make sure that PCRE 
is available in your PHP installation. It is available on most PHP servers.
Pizazz is multisite-compatible!
NOTICE: I don’t have a testing staff, and my ability to think of every 
potential problem is limited. If you have problems make sure to report them 
to me or I won’t know they exist for a long time!

Pizazz

A widget that pulls a Zazzle feed and displays products based on a query

Ads for bbPress vs Pizazz