Lisp was created in 1958, and in 2010 people are still using it to create new software. Unlike Fortran, Lisp hasn't changed radically since its inception. Programmers using Lisp in the early 1960s would still recognize the language today, although they'd probably notice that it now has a lot more convenient stuff built in.
Pretty much every high-level programming language inherits something from Lisp. It's easy to be influential when you're first, but it's impressive how many features of modern programming languages were present in Lisp back when the idea of a high-level programming language was still new.
Fortran, which predates Lisp slightly, is still in use today, but a modern Fortran program looks nothing like a Fortran program from 1957. I was at a talk a few years ago where the speaker said, "I don't know what characteristics the programming language used in HPC [high-performance computing] in 20 years will have, but I know that it will be called Fortran." He was probably quite right; the Fortran name is applied to a whole family of languages that are only superficially similar. In contrast, Lisp implementations all share the same core semantics.
You may never use any of the languages that we've discussed in this series. Even so, you almost certainly will use a language that inherits some of their characteristics. Spending some time learning where these concepts originated can help you to understand why they're in the languages that you do use.