I'm working mostly on non-Java interfaces to the ActiveMQ JMS/MQ server. In marketing speak, "ActiveMQ is a fast open source JMS 1.1 provider and Message Fabric supporting clustering, peer networks, discovery, TCP, SSL, multicast, persistence, XA and integrates seamlessly into J2EE 1.4 containers, light weight containers and any Java application. ActiveMQ is released under the Apache 2.0 Licence" What I am doing centers around the TTMP wire protocol for messaging. I don't have a really good link for that at the moment, however.
Apache ObJectRelationalBridge (OJB) is an Object/Relational mapping tool that allows transparent persistence for Java Objects against relational databases.
jDBI is designed to provide convenient tabular data access in Java(tm). It uses the Java collections framework for query results, provides a convenient means of externalizing sql statements, and provides named parameter support for any database being used.
SQLBuilder is an SQL query constructor designed for programmatic, dynamic query generation. It supports out-of-order element addition and handles prepared statement binding for its constructed queries. It is BSD-style licensed.
Aimity is a command-line AIM client in Ruby. It consists of two parts: a server which remains connected to the TOC server, prints incoming messages to stdout, and publishes a distributed-ruby interface to send instant messages; and a client program for talking to the aimity server in order to conveniently send messages. Aimity comes from my desire to access AIM while sitting at a console.