Sav Z  
   Web ORDBMS with Zigzag language for object, relational and XML data manipulation. [Free for non-commercial]
   http://savtechno.com/

StoredObjects  
   Cross-platform object relational database for Java. For beginners it is a complete development environment for writing database applications in Java without reading a manual. For experts it is a tool for developing distributed client/server groupware in
   http://storedobjects.sourceforge.net/

JGrinder  
   Initially began as a solution for Object/Relational persistence. Supporting this involved the creation of many utility classes and tools that could be used to accelerate any application development effort. [Open source, LGPL]
   http://jgrinder.sourceforge.net/

IBM Cloudscape  
   Pure java database management system for distributed, embedded, mobile computing applications. [Commercial]
   http://www-3.ibm.com/software/data/cloudscape/

FirstSQL/J  
   A pure Java fully SQL/92 compliant ORDBMS. [Commercial]
   http://www.firstsql.com/

Inprise JDataStore  
   A Pure Java, Object Relational Database Management System for use in Web, mobile or embedded database applications. [Commercial]
   http://www.borland.com/jdatastore/

Cayenne  
   An Object-Relational mapping framework working with relational databases. [Open Source]
   http://objectstyle.org/cayenne/

ObjectStore EdgeXtend  
   Provides a distributed data caching infrastructure that is automatically generated using model-driven, object-relational mapping tools. This data access and caching layer eliminates bottlenecks in custom enterprise applications by optimizing relational da
   http://www.objectstore.com/products/edgextend/