DB2 is a database management system that offers industry leading performance, scalability, and reliability on your choice of platform from Linux to z/OS. Its Web Control Center offers administrators an easy-to-use interface for maintaining databases, and can be run from any Java-enabled Web browser. For Java developers, DB2 UDB for Linux offers support for JDBC and SQLJ, and Net.Data allows for the creation of dynamic data diven Web applications. DB2 UDB for Linux allows you to harness the power of user-defined types and functions and support for Binary Large Objects.
db4o is an object database for Java and all .NET environments. Its features include ACID transactions, automatic class schema recognition, query-by-example, a S.O.D.A. object querying API, native queries, LINQ support on .NET, callback methods, memory files, cascade-on-delete, multi-threaded access, and Java Webstart and servlet support.
dbtcp is a package of libraries which provides applications on Linux access to ODBC datasources on remote machines running Windows. It allows a Linux application to access data held on a Windows machine (such as MS SQL Server on NT), and includes a command line client, a DBD, and a PHP driver.
DeleGate is a multi-purpose application level gateway or proxy server that mediates communication of various protocols, applying cache and conversion for mediated data, controlling access from clients, and routing toward servers. It translates protocols between clients and servers, converting between IPv4 and IPv6, applying SSL (TLS) to arbitrary protocols, merging several servers into a single server view with aliasing and filtering. It can be used as a simple origin server for some protocols (HTTP, FTP, and NNTP).