Offers an interface to the constraint programming library Gecode.

Commercial IDE, with integrated debugger, useful for normal and Web programming, applications. [Scriptolutions]

Analog to Perl's Inline::C, allows embedding C external module code in Ruby scripts directly; code is compiled and run on the fly, as needed. [open source, MIT License]

Integrated Development Environment, mostly a GUI wrapper of debug.rb with editor, Windows only. Screenshot, description, downloads: old, new.

Ruby Zebedee: 100% compatible clone (protocol, configuration file), can be used by Ruby scripts easily like standard Socket API. Zebedee is simple program to form encrypted, compressed tunnel for TCP/IP or UDP data between two systems.

Simple testing framework for Ruby. Descriptions, downloads.

Ruby bindings for several libraries, programs, with readme files.

Generative programming system, for genetic programming, grammatical evolution, or hybrid GP-GE; coded in all Ruby; best suited for interactive evolution and design work. Open source, GPL.

Dozens of Ruby programs. Examples: reverse dependency tool, simple HTTP daemon, vim syntax coloring, Design by Contract, Literate Ruby, Fibonacci generators, generic XML generator.

Software Archive, many projects. Examples: Racc, LALR(1) Perser generator; TMail, Mail Class (implements MIME multipart, more); strscan, extension to scan string faster. English and Japanese versions. Ruby-dev summary index. By Minero Aoki.