MAME
Frontends for Linux variants of MAME (Multiple Arcade Machine Emulator).
CXmame is a very simple and easy to use frontend for XMAME.
GNOME Video Arcade is a simple Mame frontend for any freedesktop.org compliant desktop environment.
GNOME Video Arcade recognizes that the frontend is not the point; the games are. As such, its chief design goal is to help you quickly find a game to play and then get out of the way. Its purpose is not to help you manage your ROM collection, nor to provide a confusing graphical interface for MAME's plethora of configuration options.
A KDE Frontend for XMAME. It has an interesting design, very easy to use, and configure.