The MMX Emulator library provides a simple way to (slowly) execute binaries that use MMX instructions, on processors that do not support them. It can be used if you want to develop MMX code, or execute MMX binaries, on a non-MMX Intel compatible CPU. Please note that well written MMX binaries should contain the equivalent non-MMX code, since the emulation will always be really slow, and MMX code is all about speed.
Wine is an implementation of the Windows API on top of X and Unix. It does not require Microsoft Windows, but can use native Windows DLLs if they are available. It provides both a development toolkit for porting Windows source code to Unix as well as a program loader, allowing many unmodified Windows programs to run on x86-based Unixes.
LibDsk is a library that attempts to create uniform functions for accessing floppy drives, raw "dd" disk images, and disk image files in various emulator formats. Its intended use is for emulator authors; it also includes some sample tools to read sectors from discs in CP/M, DOS, and Acorn formats. There is special-case code for direct access to the floppy controller under Linux, and to access the floppy driver under Windows. Java (JNI) bindings are included.
DirectX support for Wine is a set of patches against Wine to implement DirectX 9. It allows modern games and 3D applications to run under Wine. The patches include many experimental and beta features that have not yet made it into the stable Wine source tree. The aim of the project is to provide full support for DirectX 8 and 9 so that all games and 3D applications will run on Linux or any other platform that Wine supports.