Nintendo GameBoy
The Game Boy (Japanese: ゲームボーイ, Hepburn: Gēmu Bōi) is an 8-bit handheld video game device which was developed and manufactured by Nintendo and first released in Japan on April 21, 1989 (1989-04-21), in North America on July 31, 1989 (1989-07-31) and in Europe on September 28, 1990 (1990-09-28). It is the first handheld console in the Game Boy line and was created and published by Satoru Okada and Nintendo Research & Development 1. This same team, led by Gunpei Yokoi at the time, is credited with designing the Game & Watch series as well as several popular games for the Nintendo Entertainment System.
Emulators
VGBA
Virtual GameBoy Advance (VGBA) is a program that emulates Nintendo's GameBoy Advance on your computer. It runs GameBoy Advance games on PCs, TVs, phones, tabets, or just about any other sufficiently fast gadget.
Gambatte
Gambatte is a portable, open-source Game Boy Color emulator..
VisualBoyAdvance
VisualBoyAdvance (commonly abbreviated as VBA) is a free emulator of the Game Boy, Game Boy Color, and Game Boy Advance handheld game consoles as well as of Super Game Boy and Super Game Boy.
BGB
BGB provides an accurate emulation of the GameBoy, GameBoy Color, and Super Gameboy, based on research with lots of test roms, useful for debugging/rom development.
KIGB
One of the most accurate emulators for Gameboy, Gameboy Color and Super Gameboy for Windows, Linux and OS X.
GBA.js
Game Boy Advance in the Browser.
For legal reasons, GBA.js is presented without any included games. The emulation if fairly decent, though. Most games run and are playable.