Note: this post is from 2007, outbound links may be broken.
The Origin of Everyday Punctuation Symbols
Neatorama has an aritlce on the origin of everyday punctuation marks.
I didn’t even know the pound sign (number sign, or hash sign) was called an octothorp…
Check Neatorama for more symbols, including the question mark and dollar sign.
Link via Boing Boing