The Atom Publishing Protocol framework for Ruby aims to simplify the implementation of Atom Publishing Protocol (APP) support in Web applications. It achieves this by implementing a framework that handles the protocol-level duties for the programmer, while not making any requirements for the site design.
Binary Puzzle Solver in Ruby is an automated solver for Binary Puzzles (a kind of logic game) featured on http://www.binarypuzzle.com/. The solver contains an API and a commandline program and explains why it thinks the player should place a 0 or a 1 in the box. Although it contains only a subset of the moves the authors could think of and does not use backtracking, it was able to solve all the puzzles from binarypuzzle.com which the authors tried.
FlexiRecord is a Ruby library for object-oriented access to databases (object-relational-mapping/ORM). Each table is represented by a class, and each row of that table is represented by an object of that class. This library is especially aimed to properly support database transactions. Currently, only PostgreSQL (version 8.2 or higher) is supported as a backend.
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.
Ruby PHP Serializer is a Ruby module providing workalikes of PHP's serialize() and unserialize() functions, enabling it to manipulate serialized PHP data structures. It supports Array, Hash, String, Fixnum, Float, NilClass, TrueClass, FalseClass, and Struct, and has some support for arbitary object handling.