Roms Mania - A working online resource for roms.
AmpShell - AmpShell is a DOSBox front-end for Windows.
ROMNation - Rom download site
DBGL - DBGL is a free, open source, multiple frontends for DOSBox.
RomsGet - Download Free ROMs for NES, SNES, GBA, N64, PSX, PS2, PSP, XBOX, GAMECUBE, WII, NDS and more! Works with Windows, Mac, Linux and Android.
Terminal Launch V - For those that want a clean, simple fast emu frontend.