The best site I've found is Current Value of Old Money, a GREAT collection of links about historic money in various countries, including historic exchange rates.
From the above site, here's the link for historic
Here's a link for data from medieval
Another good link is the Marteau site, which contains information for the eighteenth century for various countries.
From the above page, here's the Marteau Prices and Wages page, which gives historical money information on
Here's a site that converts old German money to modern money (do a google search on "historical german money"): http://www.history.ucsb.edu/faculty/marcuse/projects/currency.htm#intro
The Measuring Worth site contains many calculators, as well as historical information, mainly for the
All this data can be pretty dry, but here's an article, Vulgar Economy, from the Jane Austen Centre that gives some idea of the cost of common items in Regency England.
And to end the post on a lighter note, here are some slang expressions for British money. Not all the terms are historical, but the definitions are enlightening.
Thank you all,
P.S. The above picture is old Croatian money.