This is a location (.loc) file for use with the "GTA IV Location Handler" tool by Voodoo48, main topic is Here
Download "GTA IV Location Handler" from Here
currently this file has locations for the following :
Safe Houses (100%)
Weapons (unknown % atm)
Health (unknown % atm)
Stunt Jumps (52%)
Exotic Car Exports (100%)
Text Message Cars (100%)
plus a lot more.
This is still in construction and many more additions will be added and updated in the future.