KonstantinosTourlas? reported on VisualLanguages (or diagrammatic languages), well-known examples being UML or SDL.
He particularly mentions IEC 1131-3, a family of languages designed by control engineers for developing programmable logic controller (PLC) software. Two of the four languages in this standard are diagrammatic, the diagrams being direct derivations from circuit-like and Petri-net-like notations which existed in the domain long before the introduction of programmable controllers. LabView?, geared towards domains in electronic engineering, could be taken as a further example, as could be the diagrammatic versions of Lustre and Signal.
All these languages enjoy widespread use in industry but have so far attracted only very limited interest within computing. As far as IEC 1131-3 goes, known to few computer scientists interested in safety, the focus is usually on applying formal methods around it rather than studying it as a programming language per se.
As regards the relation of DSLs to end-user programming, I believe Nardi's book, "A small matter of programming:perspectives on end-user computing", which addresses exactly this relation, to be of some interest to you. It is published by MIT press.
-- Excerpted from email by ArieVanDeursen
KonstantinosTourlas?'s remarks made me realize that the annual IEEE VisualLanguages Conferences could be strongly related to DomainSpecificLanguages.
Susan Uskudarli while at the University Of Amsterdam worked in the area of visual langauges: she has developed some techniques on specifying visual grammars (visually) in order to derive parsers and editors. (see, e.g., http://citeseer.nj.nec.com/87050.html ).
Most of her work was published in the IEEE conferences on VisualLanguages. We did not refer to those conferences in our survey, which, in retrospect and after reading your comments, strikes me as a bit odd.