DuckStation is an simulator/emulator of the Sony PlayStation console, focusing on playability, speed, and long-term maintainability. The goal is to be as accurate as possible while maintaining performance suitable for low-end devices. "Hack" options are discouraged, the default configuration should support all playable games with only some of the enhancements having compatibility issues.
XEBRA is a Japanese Playstation emulator coded by Dr. Hell. It focuses on accuracy and only outputs in native resolution.
pSX (psxfin) fully emulates the Sony Playstation. Compatibility is fairly high. An R3000 debugger is contained which may be of interest to people working on translations. An interesting emulator when it was released.
ePSXe (enhanced PSX emulator) is a PlayStation video game console emulator for x86-based PC hardware with Microsoft Windows or Linux, as well as devices running Android. It was written by three authors, using the aliases calb, _Demo_ and Galtor.
Mednafen is a portable, utilizing OpenGL and SDL, argument(command-line)-driven multi-system emulator.
MAME is a multi-purpose emulation framework.
MAME's purpose is to preserve decades of software history. As electronic technology continues to rush forward, MAME prevents this important "vintage" software from being lost and forgotten. This is achieved by documenting the hardware and how it functions. The source code to MAME serves as this documentation. The fact that the software is usable serves primarily to validate the accuracy of the documentation (how else can you prove that you have recreated the hardware faithfully?). Over time, MAME (originally stood for Multiple Arcade Machine Emulator) absorbed the sister-project MESS (Multi Emulator Super System), so MAME now documents a wide variety of (mostly vintage) computers, video game consoles and calculators, in addition to the arcade video games that were its initial focus.