Publons is a new platform that recognizes the reviews that the researchers perform for journals or conferences and discusses the latest research in their field. Anyone can create an account there and start receiving credit for a peer review that s/he has reviewed by simply forwarding the acknowledgment email s/he received from the journal/conference secretariat on to firstname.lastname@example.org.
Publons rewards you for documenting your review history by providing you with a verified record which you can use in funding and promotion applications.
You can read more about Publons as well as other methods of adding reviews here.
Related to this post see the article for recognition and Acknowledgements to reviewers of a journal