rpbs provides 'POP before SMTP' which is written by Ruby script language.
Ruby9i is a Ruby library that provides access to Oracle9i using the Oracle Call Interface. It is planned to support all major Oracle9i datatypes. If desired, its features can be accessed through a Ruby DBI-compatible API.
The Multi-User Environment Server game engine is a multithreaded event-driven internet game environment server written in Ruby and C.
Moocart is a collection of code for working with Moodle and Zencart. The primary project is Moocash: a Ruby Rails bridge between the two for automatic course enrollments.