Other software

PropEd
a universal, programmable editor in tophat for tophat
UmProf
call profiler for Umka.
StaGal
static HTML gallery generator. You can see it in action here.
COULAU
collection of Umka libraries and utilities.
minifont
5x5 font as a C header.
unifont2h
Converts GNU unifont to a c header. It can fit the whole Basic Multilingual Plane (65536 characters) into just 2 MB!
CREED (Concatenative REgex EDitor)
language for making text processing scripts.
railway simulator
Railway simulation with a builtin editor, made in tophat.