If the world (read: US) weren't so worried about proliferation, there are loads of good isotopes in spent nuclear fuel. These can be used in nuclear medicine or radiation cancer treatment. Spent fuel is (relatively) chock-full of iodine-131 (thyroid), radioactive gold (used in PET scan, I think) and cobalt-60 (cancer treatment.) I think there are bright people out there working out the engineering of all sorts of alternative energy sources, and it may end up being like the computer age meets Manhattan Project.