BoletoPHP

[UPDATE]
Since the Boleto PHP library lost traction in the community, doesn't seem to make sense in invest time on this integration. For the ones looking for some kind of functionality related to boletos, i'd suggest: https://github.com/kriansa/openboleto
[/UPDATE]

This project integrates the BoletoPHP library(http://boletophp.com.br), a Brazilian payment method(http://en.wikipedia.org/wiki/Boleto), purely into Drupal, so that any modules that needs such feature could use it, even if not related to an e-commerce website.