My first summer job while at University was with a small company in the west of England, Micross (http://www.microssautomation.com/index.php), writing industrial laundry control software, in Forth, targeting Windows NT. We used the MPE Forth system (http://www.mpeforth.com/), which was highly extensible - when you needed to add more of the Win32 API, you'd edit various files that shipped with the package and recompile the entire thing :)

The company had standardized on Forth throughout their operation, so regardless of the hardware you were using, anything from a PIC-based counting system to the Windows servers, you only needed to know one language to understand the code. Clever stuff.