Sanewall is a firewall builder for Linux that uses an elegant language abstracted to just the right level. This makes it powerful and easy to use, audit, and understand. It allows you to create very readable configurations even for complex stateful firewalls. Sanewall can be used for almost any purpose, including control of any number of internal/external/virtual interfaces, control of any combination of routed traffic, setting up DMZ routers and servers, all kinds of NAT, providing strong protection (flooding, spoofing, etc.), transparent caches, source MAC verification, blacklists, and whitelists. Newer versions abstract the differences between IPv4 and IPv6, allowing you to define a common set of rules for both, while permitting specific rules for each as you need. Sanewall is a fork of FireHOL and can make use of existing FireHOL configurations.
Ackr is a very small subset of grep/ack/rak, for lazy developers. grep is a great tool, a very powerful tool, but often too powerful for simple needs. Ackr looks for a search string in all text files and in all subfolders from the working directory, is case insensitive, has no options, doesn't look into hidden folders/files, and displays the search term in a bold font.
Auto Multiple Choice (AMC) is a piece of software that helps you to create and manage multiple choice questionnaires, with automated marking. Tests can be written in plain text or LaTeX. Automated correction and grading is performed from scans of the answer sheets using optical mark recognition.
objSQL is a PHP-based database access layer for multiple database servers. Primarily designed for small-to-medium projects, it uses an "Object Based" approach for handling general database queries. Built-in support for transactions and prepared statements allow for a common interface to all supported database types. Recordset paging is simplified by incorporating the paging method along with many helper methods for general queries. objSQL is easily extended to create your own unique classes and methods.
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.