Frontends are programs that allow a user to execute a program, usually a command-line one, using an interface. Examples of such are shown below.
ePSXeCutor[]
ePSXeCutor is a configuration utility for the ePSXe emulator (and maybe for PCSX-R too?) this comes in handy if you are juggling with many psx games and plugin configurations and want specific settings for each individual game and an easy way to swap between settings. It also allows for easy memory card and savestate managing. Latest version is ePSXeCutor 1.0.6.3.