Stamps are a great way to allow for peer feedback. I'd like to suggest a couple of ways to make them even more powerful, by tying them in to other Moodle features:

1 - Allow "Give Stamp" as an Advanced Grading method. This should include being able to make submissions available to students to read and grant stamps. Ideally, this would address the request for being able to use Stamps in a Forum module if Forum is updated to use Advanced Grading.

2 - Create a "Received n Stamps for This Activity" Completion Criterion.
3 - Create a "Gave n Stamps for This Activity" Completion Criterion.

(Allow both of these to be used together, similarly to how Forum can track both initial thread posts and reply posts.)

Creating these Completion Criteria should allow a Badge to be granted when the appropriate number of stamps have been collected.

4 - Possibly create a "Received n Stamps" pass grade criterion. We would need to think about what a "pass" grade means in terms of Gradebook integration... I suppose that should be a topic for a different tracker ticket.