When or why should I use an object database?
"db4o, an open source object database system with broad industry applicability, belongs to a popular database management systems that has close to 2 million downloads to date. Here we'll illustrate the features and application areas of such a database and compare db4o against relational DBMS/object relational (OR) mappers"
In this article Stefan Edlich and Daniel Oltmanns present us with a relative approach to object perisistence where, instead of positioning object databases as superior, they follow Ted Neward's ideas around persistence where there's a "right solution for the right problem". After these introductory ideas they use db4o to present the advantages of the object persistence engine and compare them to popular alternatives such as Hibernate.
http://dotnet.sys-con.com/read/497141.htm