GTA IV RP Mods
ELS + TRAINER
Daimyo's RPG Pack (LCPDFR)
Stealth Multiplayer (GTAGarage)

LCPDFR.com :
Speed radar
Spotlight
Door Ajar Chime + Seatbelt Chime
VehicleSpeedControl
More Realistic Gunplay and Accuracy
Spitfire7's Realistic Vehicle Bullet Damage
NoControl

GTA4-MODS.com :
Less Overtaking
Engine Blow-Out