Gfig is a "vector like" drawing plug-in for the gimp. It allows you to draw simple shapes and then "paint" them onto a canvas. The program is similar to xfig (but not as powerful) but uses the "GIMP" as its drawing engine.
xmlto is a front-end to an XSL toolchain. It chooses an
appropriate stylesheet for the conversion you want and applies it using an external XSL-T processor.
QNmap is just another X nmap frontend. The main difference, as far as I know, is that it can be run as a non-root user with some functionality It will eventually incorporate all of nmap's documented features and will be updated to reflect newer versions.