Actually, you probably don't want an appliance powered by a black hole, because those convert matter into energy via Hawking radiation and the energy output actually ramps UP as the size decreases. A very small black hole, say, 1 kg in weight (a little over 2 pounds) would convert itself into energy in about 84 attoseconds and release the same energy as a 21 megaton nuke or so.
You'd need a pretty big one for it to be stable, and I doubt you really want a vacuum cleaner weighing as much as the Everest :p
On the other hand, if we ever tame one, it would make an awesome source of energy for something that needs a lot more energy. Such as a continent. Or a warp-capable ship. Hmm, the Romulans were up to something.
Of course, it would still be a Tamagochi that blows up with the fury of a supernova if you forget to "feed" it, but, hey, it's all good as long as we call it a warp core breach. Right?
Hmm, maybe I shouldn't have mentioned Romulan singularity warp cores though... I hear the Tal'Shiar are nastier than the NSA and CIA put together ;)