Wzonka-Lad
Shareware emulator for Amiga.

GBMac
Shareware emulator for MacOS.

Virtual GameBoy
Commercial emulator for Win32 and freeware emulator for AIX, FreeBSD, Irix, Linux, MacOS, OS/2, OSF/1, Solaris, and SunOS.

NO$GMB
Shareware emulator for DOS and Win32.

KGB
Freeware emulator for Win32.

Gameboy 97
Open source emulator for DOS.

DreamGBC
Freeware emulator for Win32.

HelloGB
Freeware emulator for Win32.

TGB
Freeware emulator for Win32.

Victoly Boy
Freeware emulator for MacOS.

cingb
Open source emulator for DOS and Unix.

Game Lad
Freeware emulator/debugger for Win32/DX8.

Boycott/MacOS
Boycott port for MacOS.

D-Boy
Freeware emulator for DOS.

AmiGameBoy
An open source emulator for Amiga.

UGE-Unamed Gameboy Emulator
Open source emulator for Win32 written in Pascal.

gnuboy
An open source emulator for BeOS, DOS, Linux, Windows, and Unix.

QuantumGB
Freeware emulator for DOS.

Gngb
Open source emulator for Linux using SDL.

GooBer
An open source emulator for Linux.

confusionGBx
A freeware emulator for Windows.

PlayGuy
A freeware emulator for Windows.

GEX
A freeware emulator for Windows.

KiGB
A freeware emulator for DOS, Linux/i386, MacOS, and Windows.

VisualBoy
A freeware emulator for BeOS/x86, Linux/i386, and Windows.

Phoinix
An open source (GPL) emulator for PalmOS.

BGB
A freeware emulator for Windows.

GEST
An open source emulator for Windows.

GEM
A freeware emulator for MSX-DOS2 written in assembly.

Emulation Heaven
Offers forum discussing emulator help, games, and Game Boy Advance.

GBE
Open source port for AmigaOS.

BasicBoy
An open source emulator for Windows written in Visual Basic 6 and VB.NET.

BoycottAdvance/SDL
Multi-platform emulator available for Linux, BeOS, WIN32 and FreeBSD.

Geek.com: Goby
Review of a commercial emulator for EPOC.