What should be in the stimulus bill? Moody's Economy.com rates the multiplier effect of items that might be in the stimulus bill. (bigger is better) Measurements are 1 year after the money is spent.

1.73 food stamps
1.64 unemployment benefits
1.59 infrastructure spending
1.36 aid to state governments
1.02-1.26 tax rebates
0.27 - 0.33 business tax breaks (accelerated depreciation)

A couple of weeks ago, Nobel Prize winning economist Paul Krugman estimated infrastructure spending at 1.50 and tax cuts at 1.00.

[1] [2]

[1] http://money.cnn.com/2008/01/29/news/economy/stimulus_analysis/index.htm
[2] http://www.economy.com/mark-zandi/documents/Small%20Business_7_24_08.pdf