I remember seeing, a long time ago, a PBS documentary on the English language called "The Story of English", narrated by Robert MacNeil of the MacNeil-Lerher report. It was utterly fascinating to me, especially the parts about Anglo-Saxon, the root of English brought to England by the people from the northwestern part of present-day Germany and Holland who invaded in the centuries after the Romans left. Especially cool was the part about Frisian, still spoken in northwestern Holland, which even today is similar enough to English that recognizeable English sentences can be written in it.
Since then, I've read Bill Bryson's "The Mother Tongue" and dug into the old English roots of Tolkien's work through Professor Tom Shippey's books "The Road to Middle Earth" and "Tolkien, the Greatest Author of the 20th Century". It reamains a fascinating topic to me.
I didn't every expect to see the documentary again. It is damn near 20 years old now, and I have not seen it in the documentary sections of the DVD stores. On a whim, I recently did a search for the series on Amazon, and it was available! Still on VHS, and costing nearly a hundred bucks, but I bought it anyway and it's just as good as I remember. I'd forgotten the interesting sections on the influence of Cockney and the "Guid Scots Tongue" (and if you know me, you know why the Scottish stuff is interesting to me ;)