FREE DATASETS
FEC Data
SIC Codes
Zip codes and Avg AGI with *some* metro areas included, available
through my google docs:
Zip code data that includes lattitude and longitude for each
Most expensive zip codes, according to Forbes. From my google docs.
Various demographic data by zip
(The source of this data is MS MapPoint. It was exported to csv from the
application. Also from my google docs.)
Census population data
Various stuff here:
FREE DATA IN UNFRIENDLY FORMATS
The poorest and wealthiest places in the United States
(and other links possibly of interest at top right of page)
Regional employment data
Zip codes