Turba is the Horde contact management application. It is a production level address book, and makes heavy use of the Horde framework to provide integration with IMP and other Horde applications. It supports SQL, LDAP, Kolab, and IMSP address books.
4Suite is a Python-based toolkit for XML and RDF application development. It features a library of integrated tools for XML processing, implementing open technologies such as DOM, RDF, XSLT, XInclude, XPointer, XLink, XPath, XUpdate, RELAX NG, and XML/SGML Catalogs. Layered upon this is an XML and RDF data repository and server, which supports multiple methods of data access, query, indexing, transformation, rich linking, and rule processing, and provides the data infrastructure of a full database system, including transactions, concurrency, access control, and management tools. It also supports HTTP, RPC, SOAP, and FTP, plus APIs in Python and XSLT.