Cetus  
   Link collection with FAQs, newsgroups, books, and conferences.
   http://www.cetus-links.org/oo_data_bases.html

Object-Oriented Databases versus Object-Relational Databases  
   Gives a rough definition of relational, object-oriented and object-relational databases and compares these paradigms using criteria such as simplicity of use, scalability and maturity.
   http://www.cai.com/products/jasmine/analyst/idc/14821Eat.htm

Object-Oriented Database Management Systems  
   A collection of links, background, research, requirements, books, newsgroups, and organizations. Includes pointers to the three manifestos.
   http://www-2.cs.cmu.edu/People/clamen/OODBMS/

Ultima-S: Problems and Decisions  
   Advantages of a client-server O(R)DBMS versus a mainframe database are shown.
   http://ivn73.tripod.com/ultima.htm

The Object-Oriented Database System Manifesto  
   Defines the main features and characteristics that a system must have to qualify as an object-oriented database.
   http://www-2.cs.cmu.edu/People/clamen/OODBMS/Manifesto/htManifesto/Manifesto.html

Whatever Happened to Object-Oriented Databases?  
   Comparison of state and future prospect of object-oriented and relational databases. [PDF file with IEEE Computer version available from same site.]
   http://www.leavcom.com/db_08_00.htm

ODBMS Articles and Products  
   Articles on object-oriented database systems architecture and technology, product comparison and selection as well as a small FAQ.
   http://www.service-architecture.com/object-oriented-databases

Object Data Management Group (ODMG)  
   Industry association for a common OO data standard. Extracts of ODMG 3.0 as well as some explaining articles are online. Note: Standard is partially superceded by JDO.
   http://www.odmg.org/

Informix Corporation  
   Designs, develops, manufactures, markets, and supports database management systems and object-oriented application development tools for delivering information to desktop platforms. (Nasdaq: IFMX).
   http://www-3.ibm.com/software/data/informix/