From the KiCAD homepage at www.kicad-pcb.org, select "Discover" > "External Tools" to see http://kicad-pcb.org/external-tools/.
I know, from watching this Forum, there are many other Python scripts and applications created by users from time to time. Of course, some are redundant, some are outdated, and some fit a very specialized niche. I tried a couple of the BOM formatters and decided they didn't fit my requirements closely enough to be useful. I also used a DXF export tool that was superior to KiCAD's native DXF exporter, but haven't had a need for it beyond a one-time requirement.
I don't believe anybody has tried to assemble a listing of what's available much less actually catalog them.