Considered by many to be the canonical example of a BadProgrammingLanguage (a category which excludes purposefully EsotericProgrammingLanguage''''''s 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.

''BancStarLanguage:CommaSeparatedValues::XsltLanguage:ExtensibleMarkupLanguage''

http://web.archive.org/web/20050313023432/http://www.geocities.com/ResearchTriangle/Station/2266/tarpit/bancstar.html
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CategoryProgrammingLanguage (sort of)