The 64 Studio Platform Development Kit (PDK) is a version control system for GNU/Linux distributions, allowing the creation and management of many different projects, based on Debian and Ubuntu sources. PDK is written in Python, and the source code is well commented and contains documented examples.
Hardened Debian improves Debian GNU/Linux with high security and hardening features, hardened kernels and packages, DHKP, and other security related enhancements. It makes systems more difficult to compromise using common attacks such as race conditions, chroot jail escapes, and buffer overflows.
HelenOS is a microkernel-based multiserver operating system designed from scratch. By decomposing the operating system functionality into tens of isolated but intensively communicating userspace servers, it provides a computing environment that has several virtues such as flexibility, increased robustness, well defined explicit interfaces, and smaller complexity of individual components. HelenOS does not aim to be another clone of Unix or some other legacy system and is not POSIX-compliant (even though it may seem POSIX-similar at times). Instead, the goal has been to design it according to what is the most elegant and right thing to do. What makes HelenOS unique among the other multiserver operating systems is its multiplatform and multiprocessor microkernel. It will run on seven different processor architectures ranging from a 32-bit uniprocessor little-endian ARMv4 to a 64-bit multicore big-endian UltraSPARC T1.
Ketchup is a tool for updating or switching between versions of the Linux kernel source. It can find the latest versions of numerous kernel trees, calculate which patches are needed to move to that version, download any patches or tarballs that aren't cached, check GPG signatures where available, and apply and unapply patches to get the desired result.
OpenVPS is a set of software built on top of the Linux VServer aimed specifically at Web Hosting. It is not another set of kernel patches, but a set of scripts to create virtual servers, collect resource utilization information, and provide an interface to the customer as well as the administrator.
dstat is a versatile replacement for vmstat, iostat, netstat, nfsstat, and ifstat. It includes various counters (in separate plugins) and allows you to select and view all of your system resources instantly; you can, for example, compare disk usage in combination with interrupts from your IDE controller, or compare the network bandwidth numbers directly with the disk throughput (in the same interval).
Moodss is a modular monitoring application, which supports operating systems (Linux, UNIX, Windows, etc.), databases (MySQL, Oracle, PostgreSQL, DB2, ODBC, etc.), networking (SNMP, Apache, etc.), and any device or process for which a module can be developed (in Tcl, Python, Perl, Java, and C). An intuitive GUI with full drag'n'drop support allows the construction of dashboards with graphs, pie charts, etc., while the thresholds functionality includes emails and user defined scripts. Monitored data can be archived in a SQL database by both the GUI and the companion daemon, so that complete history over time can be made available from Web pages or common spreadsheet software. It can even be used for future behavior prediction or capacity planning, from the included predictor tool, based on powerful statistical methods and artificial neural networks.