UML2SQL
Synchronizes UML diagrams with database structures. [Open Source, LGPL]

CrossDB
An open source Java API for writing object oriented SQL statements that will run on any database. [Open source]

myTextReport
Creates flexible reports from mySQL databases in any ASCII-based format, like HTML, RTF, TEX, Postscript, VRML... whatever. Just edit a template-file and insert special-coded, even relational SQL-statements. [Open Source, GPL]

FireStorm
Generates database persistence logic based on relational database schema. Generates DAO, EJB and JDBC code.

The Apache DB Project
Project charged with the creation and maintenance of commercial-quality, open-source, database solutions. Mailing list signup, guidelines, repositories, and proposals.

Java Client Database (JCDatabase)
A simplified version of JDBC that runs on both the server and as part of client applications. [Commercial]

Java Database Tools, Products and Resources
Extensive list of utilities for OO, OR and relational database application development in Java.

SQL2JAVA
Introspects database schema and generates all the needed java code to access it. No XML, no manual mapping, no complex architecture, no hand coded queries. [Open source, LGPL]

JSQL Product Suite
Classes for RDBMS server support, such as connection pooling, authentication, and caching. [Commercial]

Eclipse Database
An advanced data modeling Eclipse plugin which allows: Data modeling, reverse/forward, generate DDL to SQL files, dictionary validation, working with 23 RDBMS (MySQL, DB2, Oracle), database console, working at three levels (diagrams, wizard, XML or Velocity templates). By Omondo. [Open source, LGPL, free and commercial versions]

PoolMan
Offers configurable JDBC pools to multiple databases and SQL query/ResultSet cache. Generic Java object pooling is also available. [LGPL]

SQL Pretty Printer
Takes SQL statements as the input and then presents it in a structured way complete with proper indentation for sub clauses and capitalization of keywords. [Commercial]