LMDB is an ultra-fast, ultra-compact key-value data store developed by Symas for the OpenLDAP Project. It uses memory-mapped files, so it has the read performance of a pure in-memory database while still offering the persistence of standard disk-based databases, and is only limited to the size of the virtual address space (it is not limited to the size of physical RAM).
Build Gear is a lightweight build tool for building embedded firmware. Its primary focus is to make it easy to create and maintain fully-customized embedded firmware. This is reflected in a straightforward commandline interface and support for easy-to-understand build files. The secondary focus is build performance and build integrity. Build Gear is easy to use and well-suited for rapid prototyping and product development of GNU/Linux firmware to be deployed in small-to-medium-sized embedded systems.
ack is a tool like grep, optimized for programmers. Designed for programmers with large heterogeneous trees of source code, ack is written purely in portable Perl and takes advantage of the power of Perl's regular expressions. It searches entire trees by default while ignoring Subversion, Git, and other VCS directories and other files which aren't your source code. It uses Perl regular expressions to find just what you want.
ENet for C# wraps the C-language ENet networking library. For games and other realtime applications, if you use TCP, old data can hold up newer data, even if it is no longer relevant (old positions, etc.). Your players will perceive any lost packet as a "lag burst". ENet supports multiple in-order streams of data, and allows you to decide on reliability on a per-packet basis. The library is useful for both client-server and peer-to-peer architectures.
CryptSharp provides a number of password crypt algorithms: BCrypt, MD5 (and Apache's htpasswd variant), PHPass (WordPress, phpBB, Drupal), SHA256, SHA512, and Traditional and Extended DES. It also includes Blowfish, SCrypt, and PBKDF2 for any HMAC (.NET's built-in PBKDF2 implementation supports only SHA-1). If you are looking to store passwords, odds are CryptSharp will have the algorithm you want.
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.