Outlet tester

Inexpensive plug-in device to determine that an outlet is wired properly. See this thread for a demonstration of the value. Will not replace a VOM, but a small handy tool nonetheless. At a cost of ~ $3-$10, should be a part of everyone's toolbox.

Link to online vendors: "Electrical Receptacle Wall Plug AC Outlet Ground Tester".

For a counter-point, and specifically how this device may give false readings, see http://ecmweb.com/mag/electric_three...ircuit_tester/.
See also http://us.fluke.com/usen/Community/F...erProblems.htm on how to achieve a more comprehensive test with a VOM/DMM.