Below are multiple files off of the Rockstar servers. I will update these very often, so be sure to check back often to see what all modding opportunities you have!
You can type any specific link from Rockstars servers into your browser to view that file. Copy and paste into notepad++, format, and save as the right kind of file and you can host it on your server under the same path as it was on their servers.
If you want a specific file, or are having trouble finding a specific one, just ask me for it. If any files below are outdated, or there are more files that I can add to the list, please let me know, as well as the link to Rockstars servers where I can find them.
Clean Tunables.json currently on R* servers - (Updated 12/28/13)
Multiplayer Loading Screens Mod Pack -(Updated 12/28/13)
Includes news.json, all en.json and .dds image files for each loading screen, and a txt tutorial
More to come later...
tunables.json - we all know what this is I think (God-mode, RP, Cash, etc). Updated as of 12/28/13
Loading Screens Pack - this is a pack of all of the loading screens. This includes the news.json, all en.json and .dds images for loading screens, and a .txt file tutorial on how to edit your loading screens. Added and last updated on 12/28/13. Related post HERE
commerceData.xml - Contains info on what is in the Online Store (Cash Pack descriptions, images, names, etc). Ps3 version has been added next to it as per user request.
Please let me know when any files in this post are outdated, or there are any other files that I can put on here.