SchemaView Plus is a GUI for creating, retrieving, drawing, and printing database schema. It uses Perl, Tk, DBI, and XML packages. Schema can be retrieved using DBIx::SystemCatalog, and it uses XML for storing and retrieving data in text files. You can write any filters to modify these XML files to add new functionality based on your projects (e.g. dropping off some relationships).
dbMan is a complex SQL monitor for common database systems (PgSQL, Oracle, MySQL etc.). It's based on Perl and DBI interfaces. Features include a command history buffer, tab completion, editing Oracle objects, simultaneous connections, SQL help, importing and exporting of tables, Oracle explain plan, and more. dbMan is made as a simple kernel and many extension modules, and you can make your modules with a simple HOWTO.
The SQLB Perl module provide a simple API to interface SQL Load Balancer within Perl scripts. It allows you to interface your scripts with Oracle, MySQL, or PostgreSQL easily and efficiently. You can change your database type easily, the only changes required in your scripts being to queries with database-specific options.
WebTools is "system" of multiple modules and libraries. Along with template engine capabilities, it features session management, global variables support, cookies support, and various database interfaces. It also features a pure Perl mail client, categories management, form checking, and libraries such as a CGI-based downloading library, HTML parsers, and a library that makes PHP functions available to Perl for ease of development.