OMLET: Oracle 8i/9i Monitoring Applet
Java client that helps visualize and monitor the health of Oracle database instances. [Commercial]

DbConnectionBroker
A pure Java package for handling multiple concurrent database connections. DbConnectionBroker creates a broker with a very simple interface for handing out and returning database connections from a configurable pool of connections. Also RandomGUID (utility class generates cryptographically strong random GUIDs in the standard format). [Open source]

JDBCPool
Reuses JDBC connections to save time and to prevent exceeding connection limits which exist on certain databases. [Open Source, GPL]

JDBC API
Java Database Connectivity (JDBC) API is a standard SQL database access interface. This API provides programmers with universal access to a wide range of relational databases. (Sun)

P6Spy
Logs all queries between any JDBC application and any database with no code changes required. [Open source]

DBPool - Java Database Connection Pooling
A free JDBC connection pooling library featuring easy setup, connection validation, statement caching, time expiry. [Open source]

IronGrid, Inc
IronEye SQL: A JDBC profiling tool that allows J2EE developers to identify database performance bottlenecks by viewing the SQL that flows between an application and database through a GUI console with no code changes. IronEye Cache: Leverages IronEye SQL technology to enable intelligent, easy caching. [Commercial]

OrindaBuild
A utility that automatically writes Java code to access stored procedures, packages, functions and sequences in Oracle databases. By Orinda Software. [Commercial, with sources]

Webopedia.com - JDBC
Describes the term JDBC and lists links with additional information.

Octopus Java/XML ETL Tool
A simple Java-based Extraction, Transformation, and Loading (ETL) tool. It may connect to any JDBC data sources and perform transformations defined in an XML file. [Open source, LGPL]

FireStorm/DAO Code Generator for JDBC
FireStorm/DAO imports database schema definitions from SQL scripts or from live databases via JDBC and then generates a complete data-access tier based on JDBC.

JDBC Drivers and Vendors
A directory of JDBC-Driver-Vendors.

Java Guru - JDBC FAQ
A list of frequently asked questions about JDBC.

JDBCFacade
A library for making JDBC easier to use and less error prone while encouraging a clean separation between persistence and domain logic. [Open source, MIT License]