Ads for bbPress is a WordPress plugin by Stefano Lissa that injects ads code (and more) on bbPress pages (top, bottom and between topics and replies). You can add whatever JavaScript and HTML code you want on top and bottom of each page and between topic and reply lists.
Ad points:
before and after the single forum page where all topics are listed
before and after the single topic page where all replies are listed
before the new topic and the new reply form
between the topics and the replies blocks
just before and after the single reply text
Download: https://wordpress.org/plugins/ads-bbpress/
