Injecting ads on bbPress pages is now really easy with Ads for bbPress.
This new free plugin can inject, like Header and Footer whatever code you need before and after the bbPress pages not not only. It can inject between topic and replies and before the new topic and new reply form.
A must have for everyone running bbPress.
And it’s ultra light: the best practices have been used to load the blog as less as possible.
Find it on WordPress here.