TooN is a very efficient numerics library for C++. The main focus of the library is efficient and safe handling of large numbers of small vector matrices and providing as much compile time checking as is possible. The library also works with large vectors and matrices and integrates easily with existing code. In addition to elementary vector and matrix operations, the library also providers linear solvers, matrix decompositions, optimization, and wrappers around LAPACK.
extract_url.pl is a Perl script that extracts URLs from either correctly-encoded MIME email messages or from plain text. It can be used either as a pre-parser for a URL selector (such as urlview), or as a standalone URL selector. It is very configurable, can handle URLs that have been broken over several lines in format=flowed delsp=yes email messages, and eliminates duplicate URLs. It was designed primarily for use with Mutt, but can be used by for any similar purpose. The idea is that if you want to access a URL in an email, you pipe the email to a URL extractor (like this one), which then lets you select a URL to view in some third program (such as Firefox).
NetIRC2 is an easy-to-use .NET IRC client library. It supports all major features relevant to making a chat client or bot. It has full support for synchronization contexts. You can use it from a Windows Forms or WPF GUI thread and chat events will be automatically dispatched, allowing you to completely ignore multithreading. It uses byte arrays internally, so mixed encodings can be handled. The IrcClient class can even be used as a component in the Forms Designer. Because it speeds up connect times with some IRC servers, an Ident server is included as well.
Premake is a build configuration tool. Describe your C, C++, or C# software project using a simple, easy to read syntax and let Premake generate the project files for Visual Studio, GNU Make, Xcode, Code::Blocks, CodeLite, SharpDevelop, or MonoDevelop. Premake allows you to manage your project configuration in one place and still support different build systems. It allows you to generate project files for tools that you do not own. It saves the time that would otherwise be spent manually keeping several different toolsets in sync. And it provides an easy upgrade path as new versions of your favorite tools are released.