Banc Star Language

Considered by many to be the canonical example of a BadProgrammingLanguage (a category which excludes purposefully EsotericProgrammingLanguages like InterCal and such). This beastie was used for production work at a major US bank. In fairness to its creators; it was originally intended as an IntermediateLanguage of sorts (to be generated only by a UI-building tool) but for some reason it got turned into a source language.