This is the most extensive I've ever found, Ed. I think it was Gargoyle who first posted it here and it is incredible, linguistics and every language immaginable. Watch for all of the links, as there are many, just click here.This one is a dictionary of slang posted by someone else here, can't remember who.
Here is a Dictionary of Phrase and Fable
And, this one will take you to a Weekly Origin of Words Webzine.
There is another I used to subscribe to via email. He asnwers these kinds of questions all of the time. I cannot find the bookmark. When I do, I will post it for you.
what fun!
kat