PatchIt! is created for software developers, this is a two part program that is used to make patches for updating software. Both the manager and the actual patch-program are easy to use GUI-programs. Command line switches are not necessary on the user"s end but it"s available. PatchIt! compares old files with new files, and picks the difference and includes that in a patch-file, which you distribute together with the actual patch-program.
..so instead of putting the whole new version online which may have a size of 3mb, you make a patch file with this great tool and put a file online which have a size of i.e. 350kb. ..isn"t that great!?