Your Taxes - Ike to Obama

IRS - tax rates, exemption amounts, deduction amounts, algorithms for calculating taxes (in the Form 1040 instructions for each year)
See for example: Instructions for Form 1040 1988
Also see:
Inflation-adjusted items for 2009
Standard, Itemized, and Total Deductions Reported on Individual Income Tax Returns, 1950-2006
U.S. Bureau of Labor Statistics (BLS) - CPI (Consumer Price Index) data used to adjust for inflation.
See also their CPI Inflation Calculator
U.S. Social Security Administration - payroll tax data (rates, maximum income subject to tax, etc.)
U.S. Census Bureau - median 2007 household income is $50,233:
"Among the race groups and Hispanics, black households had the lowest median income in 2007 ($33,916). This compares to the median of $54,920 for non-Hispanic white households. Asian households had the highest median income ($66,103). The median income for Hispanic households was $38,679."