Minimal Cart is a minimal shopping cart implementation plugin for Ruby on Rails that includes a basic shopping cart, product management, shipping / tax management and payment processing via ActiveMerchant.

Minimal Commerce is a full stack, turn key shopping cart system that uses the Minimal Cart plugin (http://github.com/endax/minimal-cart).

Minimal Track is a Ruby based binding for the various package tracking APIs (FedEx, UPS, etc.). Still currently under development.

Red Vector is a VSM/SVM based gem for similarity / classification / spam detection etc. Still currently under development.

Bulletproof is a fairly minimal threaded load/stress testing framework that was originally designed to be used with Mechanize scripts for load testing N number of simultaneous of hits on a web application, but can potentially used with any ruby script.