GTAIV Moding Tools
Xbox Image Browser
Used to replace files within the GTA IV ISO.
https://www.dropbox.com/s/blgh4954n0m8hw7/Xbox%20Image%20Browser%20v2.9.0.350.zip
ABGX360
Used to verify the ISO is safe for Xbox Live and makes sure it's not corrupt.
https://www.dropbox.com/s/ywruhl8tbzkvx2e/abgx360%20v1.0.6%20Setup.zip
ImgBurn
Used to burn the ISO to a disc.
https://www.dropbox.com/s/j7oq8drf1rd2yfm/ImgBurn%20v2.5.7.0%20Setup.zip
Horizon 360
Used to mod the GTA IV single player gamesave.
https://www.dropbox.com/s/kezgbezmeuw274d/Horizon360%20v2.5.10.0%20Setup.zip
GTA IV Xbox File Editing Programs
General
OpenIV
Use this to open the GTA IV .rpf and .img files, it also lets you extract and replace files within the archives. This will be needed to edit or make your own custom mods.
https://www.dropbox.com/s/rjbjev09i6hzvuf/OpenIV%20v1.3.5.zip
SparkIV
Alternative to OpenIV and will also open up GTA IV .rpf and .img files and will let you extract / replace files.
https://www.dropbox.com/s/9sbf6he858f5rr0/SparkIV%200.7.0%20Beta%201.zip
GTA IV .exe files
This is for OpenIV and SparkIV, you will need these for the programs to run correctly, just place these in the directories where you installed / stored OpenIV and SparkIV.
https://www.dropbox.com/s/2krg6ksiw5xtc22/GTA%20IV%20EXE%27s.zip
Other File Editing
IV Needle
All in one editing program, with this you can edit a variety of the files within the common.rpf
https://www.dropbox.com/s/8w4iavq3g7hb31l/IV%20Needle.zip
Placement Editor v1.3
Can be used for map placements
Virus Scan
Download
Placement Tool v2.2
Can be used for map Placements
https://www.dropbox.com/s/68fidivp1sik1tx/Placement%20Editor%20v1.3.zip
GTA IV Console Texture Editor
Can be used to edit the .xtd texures for GTA IV
https://www.dropbox.com/s/p8frgb5ivrvzudu/GTA%20IV%20Console%20Texture%20Editor%201.0.zip
X Train Track Editor v1.5
Can be used to edit the subway train / plane routes
https://www.dropbox.com/s/5azdb4sinudvzpg/X%20Train%20Track%20Editor%20v1.5.zip
X Handling Editor v1.0
Can be used to edit the handling file
https://www.dropbox.com/s/w6grynab1eqg7jc/X%20Handling%20Editor%20v1.0.zip
X GXT Editor v2.2
Can be used to edit the text ie. loading screen text
https://www.dropbox.com/s/idk8245a6gmgn6t/X%20GXT%20Editor%20v2.2.zip
X Car Color Editor v1.0
Can be used to edit the car colors
https://www.dropbox.com/s/zua2jw7t26bsi3i/X%20Car%20Color%20Editor%20v1.0.zip
Trickser 3rd Car Spawn Tool
Can help you with making car spawns
https://www.dropbox.com/s/tqng0i1j2b3sqnz/Trickser%203rd%27s%20Car%20Spawn%20Tool.zip
Scripting / Coding
Notepad++
Use this to code GTA IV scripts, save them as .c or .cpp
https://www.dropbox.com/s/80f9lwcoq7a563b/Notepad%2B%2B%206.2.3.zip
ScoCompiler GUI v1.2
Use this to compile .c or .cpp to .sco, this is probably the best if you're want to compile a single file.
Virus Scan
Download
Black Berry Kush Compiler
use this to compile .c or .cpp to .sco
https://www.dropbox.com/s/3vlfkobmzjryjsp/Rev%27s%20Black%20Berry%20Kush%20Compiler.zip
Sco Compressor
Use this to compress your .sco files
https://www.dropbox.com/s/efpb11j6a14y6pq/Sco%20Compressor.zip
SCO Tool Box 1.2.7
Use this to view and edit .sco files
https://www.dropbox.com/s/25zyayzyoy77y6m/SCO%20ToolBox%20v1.2.7.zip