Huh? How did you narrow it down to just GIMP? Are you excluding all non-GUI software or something? GUI has never been a big focus for GNU (which I assume is what you’re referring to when you say FSF), though they do have a couple of projects like GIMP and GNUCash. Most notably as far as GUI is concerned, they instigated the GNOME project, though they later split off. But yeah, they still maintain extremely important tools, especially for developers and UNIX systems, such as glibc, coreutils, gcc, emacs, gdb, make, bash, grub, octave, guix, etc.