OSS projects Wilcox Technologies uses every day.

  1. System Software
  2. Software for Mac OS
  3. Software for FreeBSD / NetBSD
  4. Software for Development
  5. Other Open-Source Software

Below is just a sample of the projects we use in daily operations at Wilcox Tech, along with a brief description of where and why we love it.

We use FreeBSD on most of our mission-critical infrastructure. FreeBSD is powering all of our internal database servers, our internal and external facing DNS servers, and some of our workstations. FreeBSD's community and flexibility make it great for serving.
We use NetBSD for some of our development workstations, and for testing portability for all of our applications. NetBSD's wide hardware support make it great for development.
We use Darwin, as the foundation of Mac OS X, extensively. Most of our workstations are Macs, and they all have some version of Mac OS X installed (even if it is not their primary OS). Darwin's innovative merging of FreeBSD and Mach, POSIX compliance, and easy-to-use IOKit framework for device drivers, make it great for general computing tasks.
We use Xen for all of our server virtualisation. More than 80% of all servers in Wilcox Technologies are virtualised, and they are all running atop Xen. Xen's performance and compatibilty with many types of system software make it great for server virtualisation.
We use Audacity for editing and mixing sound for our video tutorials. Audacity's great feature set and ability to use Apple Audio Units make it great for audio production.
We use Firefox for all of our Web browsing. Sure, sometimes we reach for the compass (especially for its Web Inspector), but we always find ourselves coming back to Firefox. Customisation, flexibility, the large extension community, and great performance make Firefox great for browsing the Web.
We use Graphviz for everything from software architecture diagrammes and infrastructure planning to dependency graphs and team charts. Graphviz's simple language and wide output format support make it great for making all kinds of graphs.
We use MacVim for writing code, TeX, Graphviz source, letters, and even this page. MacVim's integration with Mac OS and Services make it great for text editing of all kinds.
The Unarchiver
We use The Unarchiver for all the archive formats that Mac OS X doesn't understand natively. Support for LZMA/XZ is especially important to us, and is very performant in The Unarchiver. Its performance and wide support of formats make it great for unpacking everything.
We use ImageMagick for server-side processing of images. Its large number of transforms and effects, and its performance, make it great for editing and resizing images.
We use PostgreSQL for all but the simplest relational databases. Its great feature set, cross-platform and cross-language client API, great support, and performant engine make it great for any data set.
We use Clang on all of its supported platforms (and even a few that aren't) because it is consistently faster than other compilers and generates smaller and more efficient code. Its efficiency, platform support, and open-source license make it great for most codebases.
We use CMake in all of our cross-platform software projects, including Auctions and eScape. Its integration with platform technologies like Xcode, Qt, and KDevelop make it great for any cross-platform software project.
We use Django for our storefront and our support site. Its flexibility and concise template language make it great for Web development.
We use Doxygen on most of our software projects. Its ability to generate documentation from many languages and output to many formats (including HTML and LaTeX) make it great for documenting our APIs.
We use Git for every project we have; the last of our other repositories was converted to Git in early 2012. The fact that it runs everywhere we do (including older version of Mac OS X, and NetBSD) combined with the powerful featureset make it great for versioning code and documentation.
We use Rails for our main Web site (you can also view the source code) and our open-source software development tool Spark. Its DRY (Don't Repeat Yourself) constructs and small runtime make it great for Web development.
Qt Creator
We use Qt Creator on every platform except Mac OS. Its great refactoring support, integration with the Qt documentation, and autocompletion make it great for writing cross-platform libraries and applcations.
We use SQLite for storing simple object caches and user settings almost everywhere. Its unprecedented platform support (almost every platform with a C compiler), speed, and efficiency are second to none and make it great for embedding in any kind of app.