FinalBIG

necessary subdirectories for the BIG file. FinalBIG also supports adding directories and single files! I especially like the fact that you can have multiple big files open at the same time as I´m showing in the screenshot below. For the latest version (we´re usually all up-to-date though), be sure to check out http://www.wagnerma.de/
Here´s another BIG editor, by Matze. BIG files are the MIX files of Generals, as you might know. Currently FinalBIG supports opening and extracting BIG files. Extracting also supports creating all