A microcall is an XML-dialect used to communicate between a client and a server in a standard and easy-to-use way. The client part is (usually) implemented in Java and consists of a simple POJO that can understand the XML messages returned by the server response to a given call. The server part is only responsible for returning standard and correct messages in response to a given call. The server usually does a lot of work when it receives a call, but from the client standpoint, the server only returns a message explaining the result of the call.
dbMan is a complex SQL monitor for common database systems (PgSQL, Oracle, MySQL etc.). It's based on Perl and DBI interfaces. Features include a command history buffer, tab completion, editing Oracle objects, simultaneous connections, SQL help, importing and exporting of tables, Oracle explain plan, and more. dbMan is made as a simple kernel and many extension modules, and you can make your modules with a simple HOWTO.
DBPrism is an open source framework to generate dynamic XML from a database. It connects Oracle databases with Apache Cocoon, providing a high performance DBGenerator with functionality such as parallel content aggregation and ESI cache protocol. It also includes a powerlful database oriented CMS built on top of Apache Cocoon2 and DBPrism.
Zephyr Basecamp is a functioning GTK frontend and PostgreSQL backend enterprise project that gives small and midsize businesses the same level of inventory, order entry, sales tracking, and accounting functionality as would be expected from commercial applications. It has interfaces for both X11/GNOME/Linux and Windows.