mbootpack is a tool that takes a Multiboot kernel and modules (e.g. a Xen VMM or a xen-linux kernel and initrd), and packages them up as a single file that looks like a bzImage Linux kernel. The aim is to allow you to boot Multiboot kernels (specifically, Xen) using bootloaders that don't support the Multiboot standard (i.e. pretty much anything except GRUB).
Debian From Scratch is really two related components in one. First, it's a live bootable CD image that is designed to provide a full-featured kernel and rescue environment. It includes filesystem tools, editors, C compilers, Python, Perl, and everything you need to manually install Debian on a new machine. On ix86 machines, Grub is used to boot directly from the CD. There is also a program that is used to create the DFS CD images. It is highly configurable and can be used to create other custom bootable CD or DVD images. You can include whatever kernel or packages you want.
Bootchart is a tool for performance analysis and visualization of the GNU/Linux boot process. Resource utilization data and process information are collected during the boot process, and can later be displayed in a PNG, SVG, or EPS encoded chart. Analyzing the chart will help in finding opportunities for optimization.
Garbure is a collection of dedicated distributions. Each distribution provides carefully selected tools for a specific target domain, and is completed with examples and documentation. The set of distributions forms an entity, but each distribution works also on its own. All elements are arranged in the same way for each distribution.
pxe-boot is a PXE boot configuration of a Red Hat kickstart environment and another PXE boot environment of a recovery console. The Red Hat kickstart is just the standard Red Hat install boot disk (ES3.0), but it does not come with the installation files, just the install environment. The recovery console is an edited Gentoo environment with raidtools, parted, partimage, lilo, grub, and a slew of other handy recovery tools.
Kerrighed is a Single System Image operating system (SSI) for clusters. It offers the view of a unique SMP machine on top of a cluster of standard PCs. The goals are high performance of applications, high availability of the cluster, efficient resource management, high customizability of the operating system, and ease of use. It is implemented as an extension to Linux operating system (a set of Linux modules and a small patch to the kernel).
makebootfat is a tool to make bootable USB disks. It can autodetect, partition, format, and populate the USB disk in a single step without any user interaction. It can also create disk images which are simultaneously compatible with all the three USB booting standards: USB-FDD, USB-HDD, and USB-ZIP.