daemon turns other processes into daemons. There are many tedious tasks that need to be performed to correctly set up a daemon process; daemon performs these tasks for other processes. This is useful for writing daemons in languages other than C, C++, or Perl (e.g. sh, Java). If you want to write daemons in languages that can link against C functions (e.g. C, C++), see libslack, which contains the core functionality of daemon.
Hotplug lets you plug in new devices and use them immediately. That means that users won't need to learn so much system administration, since the Linux system will at least partially autoconfigure itself. Initially, hotplug included support for USB and PCI (Cardbus) devices, and could automatically configure some common network interfaces. Updated versions include IEEE 1394 (Firewire/i.Link) support and can download firmware to USB devices that need it.
runit is a cross-platform Unix init scheme with service supervision; a replacement for sysvinit and other init schemes. It runs on GNU/Linux, *BSD, Mac OS X, and Solaris, and can easily be adapted to other Unix operating systems. runit implements a simple three-stage concept. Stage 1 performs the system's one-time initialization tasks. Stage 2 starts the system's uptime services (via the runsvdir program). Stage 3 handles the tasks necessary to shutdown and halt or reboot.
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).
eINIT is an alternative init system. It's quite fast, since it can potentially be used without the help of any scripting at all, but it is still flexible and extremely modular. The focus is on speed and parallelisation, mostly with embedded devices and low-downtime servers in mind, and benchmarks do suggest that it's doing a fairly good job at that. It compiles cleanly (and should thus work, provided someone writes appropriate modules) on Linux, FreeBSD, and Darwin/Mac OS X.