History

Computer Languages History - Timeline chart, 1954 to today, printable; links to homes of many languages.
http://www.levenez.com/lang/

Wikipedia: PL/I - An encyclopedia description of PL/I history with many links to programming terms.
http://en.wikipedia.org/wiki/PL/I_programming_language

The Retrocomputing Museum - Dedicated to programs that induce sensations that hover somewhere between nostalgia and nausea. The freaks, jokes, and fossils of computing history.
http://www.catb.org/~esr/retro/

O'Reilly: The History of Programming Languages - A poster plots over 50 programming languages on a multi-layered, color-coded timeline.
http://oreilly.com/news/languageposter_0504.html

The Semicolon Wars - History and critique of disagreements over language design details, citing some specific traits; by Brian Hayes. American Scientist. <small>(July, 2006)</small>
http://www.americanscientist.org/template/AssetDetail/assetid/51982/

History and Evolution - A list of computer languages and some links to compilers for these languages.
http://www.scriptol.org/history.php

Historic Documents in Computer Science - Original, historic first documents for many early programming languages, like language manualsa, scanned and converted to PDF form.
http://www.fh-jena.de/~kleine/history/

Visual Programming Languages: A Survey - This paper by Marat Boshernitsan includes an historical overview of some of the pioneering efforts in the field.
http://nitsan.org/~maratb/cs263/

History and Comparison of Programming Languages - Papers on use history of: comments, labels, literals, parentheses.
http://www.gavilan.edu/csis/languages/history.html

A Brief History of Programming Languages - A special Byte Magazine article published for Byte's 20th anniversary special report
http://www.byte.com/art/9509/sec7/art19.htm

Diagram of Languages - Two diagrams showing how many languages are related to each other.
http://merd.sourceforge.net/pixel/language-study/diagram.html