The ft values for superallowed 0+ → 0+ nuclear β transitions are nearly independent of nuclear-structure ambiguities and depend uniquely on the vector part of the weak interaction. They thus provide access to clean tests of some of the fundamental precepts of weak-interaction theory and can even probe physics beyond the standard model. We have just completed a new survey and overview of world data on such transitions, including not just the nine cases considered in the past, but also eleven more from T = 1 parents: even-even T z = - 1 nuclei from 18Ne to 42Ti; and odd-odd nuclei from 62Ga to 74Rb. These new cases all involve more exotic nuclei and, to yield comparable precision, present real experimental challenges. Nevertheless, three of these new cases are already known well enough to contribute - together with the nine well known transitions - to the setting of limits on fundamental weak-interaction parameters. The remaining eight cases show promise for making important contributions in future. © Società Italiana di Fisica / Springer-Verlag 2005.