I 'learned' Forth decades ago (on a Sinclair ZX81, so essentially a quite horrible experience), and tripped over it again recently.. ending up ploughing through the books "Thinking Forth" and (currently) "Starting Forth" both of which are extremely interesting and so very very different to what we use these days. It very much fits into that saying "A language that doesn't change how your think about programming, isn't worth knowing". I realise now just how shallow an understanding of Forth I had as a teen, back in the day ;)
But I think the win here - these days - for Forth is in things like "running on small embedded devices".. I'm looking with interest at some of the activity around say Arduinos and am thinking that Forth is a rather nice fit for that sort of system. Have bought a kit, and am looking forwards to some non-work quality time to play further :)
(The Books I meantion can be found online very easily, but you'll forgive them for being written back in a time when systems were _simpler_ to grok ;) )