Totally shameless self promotion but if we’re talking small compilers, this compiler for a functional language to C and this type inferencer may interest folks.
Tiny CC http://bellard.org/tcc/
But so far nothing I have seen beats Joy0
[ [ [ joy0 body joy0 ]
[  ]
[ pop pop pop ]
[ cons pop cons ]
[ opcase pop opcase ]
[ body pop body ]
[ i pop joy0 ]
[ step pop [joy0] cons step ]
[  cons i ] ]
also see https://github.com/rswier/c4
One is a bit more readable then the other.
(not that c4 isn’t amazingly great, mind you)