The reciprocating saw is the grand-daddy of the jig saws. It is generally used during renovations or even demolitions, primarily because it can cut right through a wall. There are a wide variety of blades available for it, allowing it to cut most materials, notably wood, plastic pipe and even metal pipes. It is the common way to cut ventilation holes through the wall, when hole saws are not big enough or not able to cut deep enough.
Exchange-a-blade makes a new reciprocating saw attachment for a drill. It is inexpensive and is able to hold all standard blades. It is a bit hard to control and certainly does not have the power of a regular reciprocating saw, but for the handyperson who doesn't want to pay for a tool the rarely use, or even as a back-up for a professional, it does get the job done. On the other hand, you can rent a full sized reciprocating saw for very little a day.