Rules
still in development
The rules modules allows site administrators to define conditionally executed actions based on occurring events (ECA-rules). It's a more feature rich replacement for the trigger module in core.
So one can use it to customize a site without programming, e.g. you can:
• send customized mails to notify your users about important changes
• build flexible content publishing workflows
• create custom redirections, system messages, breadcrumbs, ..
• and a lot more....
Modules may use the rules module's API to provide new events, conditions and actions as well as default rules, which can be customized by users. Users can share their customizations by using the built-in import/export feature.
For a 5.x version have a look at workflow-ng, as the rules module is the renamed 6.x version of it.