On Sun, 29 Jan 2012 22:09:31 -0500, mcp6453 wrote:

Often on Holmes Inspection and This Old House, the workers use what appear to be
hammer drills as electric screwdrivers, particularly for lag bolts or long
screws. Are they really using hammer drills, or does it just sound like a hammer
drill?

They're called "impact drivers". The "impact" is radial not on-axis, like a
hammer drill. They're the greatest invention since the (female) bed warmer.