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.
qpsmtpd is a flexible smtpd daemon written in Perl. Apart from the core SMTP features, all functionality is implemented in small "extension plugins" using the easy-to-use object oriented plugin API. qpsmtpd was originally written as a drop-in qmail-smtpd replacement, but now it also includes an smtp forward and a postfix "backend".
XIST is an extensible HTML and XML generator. It is also an XML parser with a very simple and Python-esque tree API. Every XML element type corresponds to a Python class, and these Python classes provide a conversion method to transform the XML tree (e.g. into HTML). XIST can be considered 'object-oriented XSLT'. XIST also includes a cross-platform templating language, Oracle utilities, and various other tools.
Finit is a small SysV init replacement with process supervision similar to that of daemontools and runit. Its focus is on small and embedded GNU/Linux systems, although it is fully functional on standard server and desktop installations. Finit is fast because it starts services in parallel; it then supervises and automatically restarts them if they fail. This can be extended upon with custom callbacks for all services, hooks into the boot process, or plugins to extend the functionality and adapt Finit to your needs. Finit is not only fast, it’s arguably one of the easiest to get started with. A complete system can be booted with one simple configuration file.
HTML TIDY is a free utility to fix mistakes made while editing HTML and to automatically tidy up sloppy editing into nicely layed out markup. It also works great on the atrociously hard to read markup generated by specialized HTML editors and conversion tools, and can help you identify where you need to pay further attention on making your pages more accessible to people with disabilities.