Looking for the Drupal 7 version? Take a look at the Salsa Entity module.
- Signup block for supporters
- Integration between Salsa supporters and Drupal users, including profile (core) fields and Content Profile nodes (including any defined CCK fields).
- Integration between Salsa objects* and Drupal content types, including support for defined CCK fields.
- CCK types supported: text, numbers, dates and location.
- Per-role configurable Salsa groups, which users can check and subscribe directly in their profile pages.
*Only events at the moment
By mapping Salsa objects to Drupal users and nodes, you're able to freely use any of the available modules (such as Views). Any fields you've mapped to Salsa will be saved there, without sacrificing their advantages of being regular Drupal fields.
This module was not created with the objective of providing an API. For that, check the Salsa API module.
However, there is in fact an internal API which will probably not change much in the future, and that can be used by others. To use these functions, only the salsa module needs to be enabled.