Yeah those are cool languages, I am intrigued by them. So other than the bare-metal suitability of Forth, what is the killer app for postfix/concatenative lana

Yeah those are cool languages, I am intrigued by them. So other than the bare-metal suitability of Forth, what is the killer app for postfix/concatenative lanaguages? E.g., right now I'm trying to get into Erlang, because Riak.