db-backed is a Ruby library providing a convenient mechanism for describing objects bound to a backing database. This relieves the programmer from much of the tedium associated with writing programs with DB access. Instead of spending a lot of time working on code that reads data from the database, code that stuffs it into useable objects, remembering whether a particular piece of data lives in the database or not, etc., db-backed allows the programmer to simply design their database schema (with a few constraints), and write a very simple class definition which describes the mapping between database fields, class methods, and foreign key mappings.
jUDO (java Universal Data Objects) speeds up development/maintainence and removes database-vendor dependency for applications using databases. You should use jUDO whenever you don't want to use EJBs. You don't write any database code; you only have to specify the container classes and the interfaces for the models, and then jUDO creates the implementation for you runtime (no source is generated). It derives all info needed from your interfaces method names that follows name-pattern rules. In case you need some special access method, you either add a plugin for this or simply go directly against the database. jUDO is not as configurable and advanced as other much more professional software like Castor, Hibernate, etc., but since jUDO derives the database from your code, there is never a mismatch between code and database.
Berkeley DB XML is a native XML database engine for use within your product. Made available as a C++ library with language bindings for Java, Perl, Python, PHP, and Tcl, it integrates directly into your application (it is not a standalone database server). It provides XQuery access into a database of document containers. XML documents are stored and indexed in their native format using Berkeley DB as the transactional database engine.
SQLite/Ruby is a set of bindings to allow the SQLite (v 2.x) database to be used from Ruby scripts. It provides an object-oriented interface to all major functions of the SQLite API, including the create_function and create_aggregate functions. It also supports bind parameters, transactions, internal and external iterators, type translation in queries, and easy access to various pragmas.
utf8proc is a library for processing UTF-8 encoded Unicode strings. Some features are Unicode normalization, stripping of default ignorable characters, case folding, and detection of grapheme cluster boundaries. The library can be used in C programs, but most of the functionality is also available as a ruby library. For PostgreSQL, there is an extension providing a function for preparing strings in case insensitive indices. The currently supported Unicode version is 5.0.0.