OpenIV is a multi-purpose editor and archive manager for PC version of Grand Theft Auto IV and Episodes from Liberty city. OpenIV major features:

Creating and editing IMG archives (version 3)
Creating and editing RPF archives (version 2)
Viewing and extracting RPF archives (version 3)
Inbuilt viewers for common GTA IV & EfLC files (text, images etc)
Inbuilt SCO script decompiler (hight livel code generator)
Inbuilt WTD Texture editor. (Creating, Editing, properties changes etc)
Global search in all game archives
3D Viewer of models files - WDR, WDD, WFT
3D Viewer of collision files - WBN, WBD
openFormats Import/Export to allow work with GTA IV/EfLC resources in 3D editors (for example, 3Ds Max).