From Ezra Klein:

Of the stimulus bill, $289.6 billion or 36 percent, was devoted to tax cuts, of which the biggest by far was the Making Work Pay tax credit, which was a refundable tax credit of $400 for individuals and $800 for married couples filing jointly implemented by reducing tax withholding. That structure meant that a fair number of people didn’t even notice their taxes were being cut, even though the credit cost a total of $116.2 billion.
The next biggest provision was a $69.8 billion extension to a patch to the Alternative Minimum Tax (AMT), which primarily benefited upper-middle income filers. After that came $20 billion in tax credits to promote renewable energy, a $14.8 billion increase in the refundability of the child tax credit, and the $13.9 billion “American Opportunity” tax credit for low-income college students. All other tax provisions, which were mostly changes to existing credits and deductions (such as an expansion of the Earned Income Tax Credit), were less than $10 billion a piece.
Not including the AMT patch, which was widely expected to pass anyway, here’s the Tax Policy Center‘s breakdown of who benefited from the stimulus’s tax breaks:

From Ezra Klein:

Of the stimulus bill, $289.6 billion or 36 percent, was devoted to tax cuts, of which the biggest by far was the Making Work Pay tax credit, which was a refundable tax credit of $400 for individuals and $800 for married couples filing jointly implemented by reducing tax withholding. That structure meant that a fair number of people didn’t even notice their taxes were being cut, even though the credit cost a total of $116.2 billion.

The next biggest provision was a $69.8 billion extension to a patch to the Alternative Minimum Tax (AMT), which primarily benefited upper-middle income filers. After that came $20 billion in tax credits to promote renewable energy, a $14.8 billion increase in the refundability of the child tax credit, and the $13.9 billion “American Opportunity” tax credit for low-income college students. All other tax provisions, which were mostly changes to existing credits and deductions (such as an expansion of the Earned Income Tax Credit), were less than $10 billion a piece.

Not including the AMT patch, which was widely expected to pass anyway, here’s the Tax Policy Center‘s breakdown of who benefited from the stimulus’s tax breaks: