On a daily basis I work with C and a handful of modern languages. I do reach for Common Lisp and Prolog sometimes, so I'll count those. Common Lisp : many, many great things about lisp have been incorporated into modern languages, but CL still has a few unique things, and the whole is greater than the sum of the parts. It's less compelling than it was 10 years ago but some problems are expressed more wonderfully in C…
Although I haven't used Forth much since the time I implemented it on the Atari ST and used it for a commercial product, I still like to think of myself as a Forth person. It continues to influence aspects of my programming style, and can be useful to have known well in surprising circumstances; for example, I once solved a thorny problem in some rather complex XSLT by adapting a technique that's quite normal in Fort…
I'd be very curious to know what technique you used here.
I sort of stumbled on Forth recently, and while I'm not sure if I'll do anything with it, I like the philosophy behind it more than any other language I've yet found.