WolframAlpha makes “dynamic computations based on a vast collection of built-in data, algorithms and methods.” What?!?!? It computes various formulas in categories: Mathematics, Science & Technology, History & Culture, and Everyday Life.
I first heard about it in a lecture that Thomas MacEntee gave at the Ohio Genealogical Society Annual Conference several years ago. I’ve used this free tool to convert the value of historical currency to current dollars. It helps me understand the relative value of items.
Some caveats: This isn’t the only free historical currency converter on the web. Also, there’s some controversy about the accuracy of these tools viz. the variables that they employ.
1st U.S. Colored Cavalry 