Is it true that U.S. dollar was created on the Spanish coins "real de a ocho", wich were widely used in the former British Colonies?
They say that the US dollar symbol $ comes from the "Pillars of Hercules", wich were on the Spanish silver coins.
The Spanish Real had the symbol IsI , it is two columns representing the mountains wich separate Europe and Africa and a strip with the inscription in latin language "Plus ultra" (further beyond).

I could not find a better source on the web than Wikipedia (not very reliable in my opinion).
Spanish dollar
Pillars of Hercules

That's why the quarter coin (25 cents) is often referred to as "two bits" here in the US.

The sign's ultimate origins are not certain, though it is widely accepted that it comes from the symbol for the New Spanish (Mexican) peso which in turn comes from the Spanish Coat of arms The current Coat of arms of Spain was approved by law in 1981, when the present established replaced the interim version which, in turn, replaced the official arms of Francoist Spain. The coat of arms appears in the Flag of Spain. This takes the form of two vertical bars and a swinging cloth band in the shape of an S.

some more light into the matter, interesting.