Hyper Em  
   Win32 graphical frontend for any command line launched emulator.
   http://www.classicgaming.com/hyperem/

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/

Genesis LaunchTool  
   Header tool and launcher for Genesis emulators.
   http://www.classicgaming.com/launchtool/

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

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

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

Raging Dragon  
   Skinable front end for MAME, Impact and Modeler.
   http://www.oscarcontrols.com/dragon/

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

QuickPlay  
   Support for numerous systems and emulators.
   http://www.smackdown-hotel.fsnet.co.uk/

GamebaseAMY  
   A database front-end for WinUAE, featuring screenshots and information of games.
   http://www.gamebaseamy.com/