Frequently when prices get too high in some sector governments are called upon to provide subsidies to those who can't afford to pay.

In the US there are a large number of these. Heating fuel subsidies, food stamps, housing rental assistance and Medicaid (not Medicare) are aimed at necessities. There are also government subsidies such as Pell Grants to help pay college tuition. With the sudden downturn in the housing market there are proposals to subsidize existing mortgages. So these actions work?

I'm going to keep this brief and not overload the discussion with lots of statistics, so just take this as a working hypothesis. If you are especially interested in one program or another, or in experiences elsewhere, then please feel free to contribute data.