Frontends

BOSS MSX Frontend
Frontend for the fMSX emulator.
http://members.ams.chello.nl/koppejan/

EMUStation
Universal Frontend, featuring built-in IPS patcher, ZIP support, and Explorer integration.
http://zerosoft.zophar.net/emustation.htm

Game Launcher
A universal DOS front end for emulators.
http://www.dribin.org/dave/game_launcher/

GameBoy Mnu
Frontend for GameBoy 97
http://www.geocities.com/Area51/Dimension/9532/

Kemulator
A multi system open source frontend for Linux/KDE.
http://kemulator.sourceforge.net/

KStella
A KDE frontend to the Atari 2600 emulator, Stella.
http://kstella.sourceforge.net/