QuantLib is a cross-platform, quantitative finance C++ library for modeling, pricing, trading, and risk management in real-life. It is also wrapped as Python/Ruby/Scheme modules. Extensions for Excel, R, and Mathematica are available. Other such extensions are under consideration. QuantLib offers tools that are useful both for practical implementation and for advanced modeling. It features market conventions, yield curve models, solvers, PDEs, Monte Carlo (low-discrepancy included), exotic options, VAR, and so on.
openSteam is a generic e-commerce framework for Ruby on Rails. Its goal is to simplify the implementation of a Web shop. It features a generator to create a Web shop quickly, generators to create products and properties, a shopping cart, a checkout process, inventory entry for products or specific product configurations, and an administrative backend to overview customer and order information.