BUCKY Object-Relational Benchmark - A query-oriented benchmark that tests inheritance, path expressions, sets, methods, late binding, and user-defined abstract data types. The accompanying report contains some comparison results between object-relational and relational databases.
Modeling Object-Relational Databases - Explains why Entity-Relationship-Modelling is not enough for ORDBMS, shows alternatives and gives a (somewhat dated) product comparison of modelling tools.
Object-Relational DBMS - Slides of two lectures on ORDBMS and SQL3, using Illustra as example system.
Object-Relational Mapping - Information and facts about object-relational mapping products, architecture problem-solving, and direction in product comparison and selection.
Polyhedra - Memory-resident, high-speed, active, multi-platform, object-relational database suitable for developing real-time applications ranging from embedded to multi-user distributed systems.
PREDATOR Project - Open Source research database to test e.g. multiple join algorithms and optimizations of queries on complex data types. Is complete enough to run the Wisconsin benchmark. Based on SHORE. [Solaris, Windows NT]