Currency Exchange is the latest module I wrote for Drupal. It uses data from Yahoo Finance, and calculates the exchange amount if you give it one. It will also provide a link with details, charts and history from Yahoo.The module also provides a callable API for other Drupal components so they can do currency exchange on the fly. This allows things like giving estimates in other currencies for services you offer, or billing customers in a different currency (e.g. ecommerce module).