Another highly influential programming language not listed in the article is Self (http://www.selflanguage.org). Although I've taken two graduate-level courses in programming language theory, I didn't learn about Self until just a few years ago when I was bitten by the Smalltalk and Lisp bugs and started reading about the history of these languages and their environments. One of Self's most significant contributions is the idea of prototype-based programming, which is the influence behind JavaScript's traditional lack of classes (though newer versions of JavaScript have support for classes).
I don't know if Self was ever commercialized; I do know that once Java was released Sun focused much of its attention on promoting Java at the exclusion of other object-oriented environments that Sun invested in (such as the OpenStep Objective-C API, which was actually jointly developed by NeXT and Sun). But Self is probably one of the most influential programming languages; it's just a shame that this language was never brought up in any of the computer science courses I've taken.
I don't know if Self was ever commercialized; I do know that once Java was released Sun focused much of its attention on promoting Java at the exclusion of other object-oriented environments that Sun invested in (such as the OpenStep Objective-C API, which was actually jointly developed by NeXT and Sun). But Self is probably one of the most influential programming languages; it's just a shame that this language was never brought up in any of the computer science courses I've taken.