This is the sort of thing that someone like me can spend far too much time fooling around with, a calculator which will convert purchasing power through time. Enter an amount in US dollars and an initial year (as far back as 1774), then select a target year to convert the currency into.
So, for instance, a 1909 Model T Ford cost $850. Convert that to 2009 currency and you get $20,700.
In 1933, the first national minimum wage law set the minimum wage at $0.25/hr. In 2009 dollars, that would be $4.14.
In 1867, Alaska Territory was purchased from Russia for $7.2 million. In 2009 dollars, that would be $108 million.
If that seems fun, turn yourself loose on this website: The Current Value of Old Money