...
- Web User Interfaces for Administration or per-user configuration
- Open Source Solutions that integrate SpamAssassin in some way
- Statistics and Analyzers
- Central integration of sa-learn with IMAP Shared Folders
- Custom Rule-sets
- Custom Plugins
- Monitoring SpamAssassin
Commercial Services / Software
- Spam Filtering Services offered by vendors using SpamAssassin
- Connection Management Systems that add high performance blocking and traffic shaping in front of SpamAssassin
- Network Appliances that use SpamAssassin
- Windows Applications
- MacOS X Applications
- Unix Applications
- Maybe - Might Use SpamAssassin, we're not sure