If you itemize deductions and live in a state with sales tax, give the IRS Sales Tax Deduction Calculator a spin.
Taxpayers who itemize deductions on Schedule A of the Form 1040 in 2006 have the option of deducting the amount of state and local sales taxes paid instead of deducting their state and local income taxes paid. Taxpayers cannot take a deduction for both sales and income taxes.
Residents of states with no income tax should definitely look into this. If you have made some large purchases this past year, it may also be worth the effort to dig up those receipts. Via Consumerist.
We in Washington State are quite happy with the sales tax deduction. We may not have an income tax, but our sales tax is 8.9%.