But if you want to find roms best use the good old method, go to google (www.google.com) then type the systems name you want roms for follwed by the word 'roms' & you find what your looking for as its a SEARCH ENGINE.
on the other hand if you want to know some good games to play for each system then look at my suggestions
SNES (oh by where to start too many of them

)
Zelda Lttp
Super Metroid
Chrono Trigger
Terranigma
Final Fantasy 4+5+6
Secert of Mana 1+2
Secert of Evermore (i liked it)
Donkey Kong Country 1+2+3
Super Mario Allstars + World
Super Mario World 2
Super Mario Kart
F-Zero 1+2
Shadowrun (diff then gen vers but still good)
Final Fight 1+2+3
Star Fox 1+2
GENESIS
ShiningForce 1+2+3
Sonic (just about all of them)
Beyond Oasis (aka Story of Thor)
Shadowrun
Landstalker
Skeleton Crew
Streets of Rage 1+2+3
Afterburner 2
OutRun
Shinobi (just about all of them)
Space Harrier
Strider
Toejam & Earl
Phantasy Star 1+2+3
Beavis & Butthead
NES
Mario 1+2+3
Battletoads vs Double Draggon
Sweet Home
Earthbound
Adventures of Lolo 1+2+3
MASTER SYSTEM
Alex Kidd (all of 'em)
Ninja Gaiden 1+2+3
Gain Ground
Ghouls n Ghosts
Double Dragon
These are just a few to get you started with your collections.