I made this in 2011 and it must have been late at night since I sound a bit sleepy. But since I found it I thought I would post it.
We made a distinction between the statutory incidence of taxes and the economic incidence. The economic burden of taxation is shared between consumers and producers. The respective shares depend on the elasticities of demand and supply.
Taxes distort prices (and lead to an output contraction) - so they lead to welfare losses (deadweight losses). In other words, some transactions that were taking place prior to the imposition of the tax were not taking place after the incidence of the the tax. These transactions were mutually beneficial (to buyers and sellers).
Subsidies are negative taxes - so the analysis of subsidies is similar to that of taxes. We shifted the supply curve up due to the imposition of a tax. For a subsidy we would just shift it down.
PBS has a number of interesting programs on the financial crisis: