[MereInterest]

You are welcome, and I completely agree that they would work well in a fictional setting. The most obvious use would be as a compact storage of energy. If you had one strange quark replacing a down quark in a Carbon-12 atom, it would have an energy density of about 660,900,000 MJ/kg. For reference, this is about a factor of 8 more than Uranium-235, and a factor of 14 million more than gasoline.

Getting at that energy after it is stored would require a bit more handwavium, since you don't want it to destabilize (read: catastrophically explode) on common use. I could imagine using a gamma-ray laser (same principle as regular laser, but they don't currently exist) to destabilize the strange carbon.