The paper reviews experimental observations of microwave-generated plasmoids in air atmosphere, obtained from molten hotspots in various solid substrates (silicon, germanium, copper, titanium, aluminum, glass, basalt, etc.). Their dusty-plasma features are attributed to the dense nano- and micro particles detected. The resemblance between the laboratory-made fireballs and ball-lightning phenomena rarely observed in nature is illustrated. Similar experiments discussed show that thermite powders can also be ignited by localized microwaves in air as well as underwater, and generate significant heat energy and thrust. The dusty-plasma parameters are experimentally and theoretically characterized, and various potential applications are discussed (e.g. nano-powder production, deposition, material identification, combustion and propulsion).