According to Wikipedia, Americans consumed 138 billion gallons of gasoline in 2006. Now that gas is down about $2 a gallon, that puts $276 billion extra in the hands of consumers relative to what was expected earlier this year. Combine that with reductions in the price of home heating oil, plus reductions in the price of other imported commodities, and the benefit to consumers dwarfs the $150 billion stimulus package enacted earlier this year, which had the downside of coming out of the U.S. Treasury. Meanwhile, 10 year Treasury bonds are yielding under 3.4%, a potential boon for people looking to take out mortgages or refinance. (I read somewhere that the S&P 500 is now yielding more than the 10 year T-bill for the first time in many, many years; probably a great buy signal for stocks for those with courage and a long-term perspective.)
That doesn't mean that all the doom and gloom is wrong. But the declines noted above are a bright spot, at least for the U.S. economy.