DirectFB is a thin library that provides developers with hardware graphics acceleration, input device handling and abstraction, an integrated windowing system with support for translucent windows and multiple display layers on top of the Linux framebuffer device. It is a complete hardware abstraction layer with software fallbacks for every graphics operation that is not supported by the underlying hardware.
SoftHSM is an implementation of a cryptographic store accessible through a PKCS#11 interface. You can use it to explore PKCS#11 without having a Hardware Security Module. It is being developed as a part of the OpenDNSSEC project. SoftHSM uses Botan for its cryptographic operations.
TTA-based Co-design Environment (TCE) is a toolset that provides a complete co-design flow from C programs down to synthesizable VHDL and parallel program binaries. Processor customization points include the register files, function units, supported operations, and the interconnection network.
WinDriver automates and simplifies the development of user-mode Linux device drivers for PCI, CardBus, ISA, PMC, PCI-X, PCI-EXPRESS, and CompactPCI as well as USB 1.1/2.0. No internal OS knowledge or kernel level programming is required. It supports kernel 2.0.31 and above, including embedded Linux, x86 and PowerPC processors, and any 32-bit development environment supporting C or Delphi. Applications are source code compatible across Windows 98/Me/NT/2000/XP/XP Embedded/Server 2003/CE, Linux, Solaris, and VxWorks.
eCos (Embedded Configurable OS) is an open source, configurable, portable, and royalty-free embedded Real Time Operating System. It is written in C++, provides all the usual OS things. You configure the OS so that the parts you don't need aren't loaded to the embedded system. eCos is released under a modified GPL that allows for its use in embedded systems without having to GPL the embedded application.
Powertweak-Linux is a tool to tune your system to its optimal performance settings. It started life as the replacement for the now obsolete kernel option 'tune PCI bridges', and has been extended to provide more features and support more chipsets. It can also tune network/filesystem performance using /proc/sys entries, disk elevator settings, and x86 CPU registers (needs 2.2.18 or 2.4.0test kernel), CDROM speeds, hdparm type features, and Sony VAIO backlight. It has both a GTK GUI and a text-based lister.