Well, Depends what Category of Mods you want. For Weapons, there are some great Weapons of Millenia out there, on GB I think I saw Bloodzzz had uploaded a few. For Vehicles, GTAInside is your place. You get every kind of goddamn car there. There are no good ENB's out there, tho Gamemodding.net had a few good ones I believe. And your CLEO plugins, well, they are everywhere.