I just read an article in the NYTimes, "A Zealous Watchman to Follow the Money", about Earl E. Devaney, the inspector general of the Interior Department, who is now in charge of keeping track of the money paid out from the stimulus package. There are two web sites mentioned in the article, both of which will track spending and outcomes:
Recovery.gov, the Interior Department site
StimulusWatch.org, an independent site
I will definitely be bookmarking these sites and checking them often.
And along those lines, here is a site with a poster that shows federal spending:
Death and Taxes: A Visual Guide to Where Your Federal Tax Dollars Go