Fuel Prices
http://tonto.eia.doe.gov/oog/info/gdu/gasdiesel.asp

Consumer Price Indexes
http://www.bls.gov/cpi/

GDP
http://www.whitehouse.gov/fsbr/output.html

PPI
http://data.bls.gov/cgi-bin/surveymost?pc

Surface Transportation Board (STB)
http://www.stb.dot.gov/
-