PCSX2 is a PlayStation 2 emulator for Windows and Linux, started by the same team that brought you PCSX (a Sony PlayStation 1 emulator). Currently, it can emulate thousands of games at full speed
SPU2ghz is a SPU2 plugin for the PlayStation 2 emulator PCSX2 (and other that use the same plugin API). cdvdGigaherz is a CD/DVD plugin using win32 IoCtl calls to access real drives.
PCSX2 For Unix is aimed towards giving PCSX2 - The Playstation 2 Emulator - better Unix support, such as Linux, FreeBSD, and hopefully even more *nix platforms. #pcsx2 on irc.freenode.org