Another Hot Jupiter
If Jupiter and other planets formed around singularities, a Black Hole's continued presence would stabilize these planets and prevent then from completely boiling away. Radiation from a Black Hole would explain why Jupiter emits more heat than it receives from the Sun. A Black Hole's rotation would generate electric currents in the whirl of charged particles at the planet's core. This would produce a bipolar magnetic field, whose poles would not necessarily line up with the geographic poles. Existence of Black Holes within planets would explain mysteries of our Earth. A singularity could exist in the last place humans would look, beneath their feet.