Developing SAP DB: Developer information from Daniel Dittmar.
Linux Quickstart Howto (Debian): SapDB step-by-step installation guide.
MaxDB: An open, SQL-based, relational database system that provides high availability and performance scaling from small to very large implementations. [Open Source, GPL/LGPL]
Sap DB Developers's Site: Developer Helper Site with actual setup guide for linux and information about the project.