• http://www.progress.com/dataxtend/products/index.ssp

Gemstone:

• http://www.gemstone.com/products/

Tangosol (now owned by Oracle) J2EE? grids

• http://www.tangosol.com/

Ridiculously simple, Prevayler provides transparent persistence and replication for plain old Java objects. It is literally several thousand times faster than using a relational database through JDBC.

• http://www.prevayler.org/wiki/