MySQLTuner is a script written in Perl that will assist you with your MySQL configuration and make recommendations for increased performance and stability.

A fast PostgreSQL Log Analyzer

Server for the MusicBrainz project (website, API, database tools)

Bucardo multimaster and master/slave Postgres replication

Nagios check_postgres plugin for checking status of PostgreSQL databases

Pulled Pork for Snort and Suricata rule management (from Google code)

Perl DBIx::Safe module for restricting SQL to a database handle