Real world usage of concatenative programming languages

Question

What are some real-world projects done in concatenative languages like Forth, Factor, Joy, etc.?

Answer 1

factorcode.org, concatenative.org and tinyvid.tv are powered by Furnace, a Factor web server and framework.

Answer 2

PostScript is concatenative, and there's obviously a huge number of applications of PostScript. It's just not a general purpose programming language.