Extremely useful! For one, it would allow current-based forms of memory storage. Right now, non-volatile memory is always stored as a voltage*, because static

Extremely useful! For one, it would allow current-based forms of memory storage. Right now, non-volatile memory is always stored as a voltage*, because static charges can be held without decay. Superconductors allow that for current. This also is great for sensors. For example whereas a copper ring will have a brief current when exposed to a changing magnetic field, a superconductor will have a current that perfectly tracks and cancels any magnetic flux it is exposed to. It can bring AC effects down to DC. And due to zero losses (and zero Nyquist noise), it could be used to, for example, make more sensitive antennas. Secondly, even if you don't care about the losses in terms of power consumption, you almost always care about losses in terms of heat. Superconductive motor windings, for example, would allow motors to not only be more efficient, they could also be much more power-dense because of less heat generation. And then there are the really fun applications, like levitation. * (Or eg. a ferromagnet)