The PDC's Open Data portal supports both OData and SODA (Socrata Open Data API). SODA is more feature-rich. In fact, all the PDC's website features such as "Follow the money", "Campaign explorer", and "Campaign overview" are built 100 percent on the SODA API.
Our data set catalog lists all the data that is available and the metadata necessary to understand the data. There is also an introductory video on using the portal on that same page. The portal provides a nice way to explore the query capability before making API calls.
For anyone who wants to use Drupal CMS to access the API, we also have a SODA compatible data provider for the Drupal/Forena reporting engine.
We are continually looking for opportunities to publish more data. We have an open data program that is open to public participation. We want to make sure we are focused on providing the data that people need to answer the questions they have, and we welcome suggestions for enhancements of the open data program.