Additional required or recommended binaries can be downloaded for the following applications:
Kigo is a go frontend which needs a backend. To make it work properly, you need to install that backend and point kigo to it.
Kompare is a diff viewer, based on gnu diffutils.
KAppTemplate provides an easy way to generate new projects from a bunch of predefined templates.
KCachegrind is a profiler frontend. For visualization it needs graphviz.
Cantor is an application, aimed at providing a nice worksheet view to other Free Software Math packages.
Kile is a LaTex editor and Frontend
Umbrello is an UML Modeller. For auto diagram layouts it needs graphviz.