The very recent studies of two classes of transition metal oxides with a triangular metallic sublattice are reported. The first class of materials concerns the swedenborgite CaBaCo₄O₇ family, which is shown to be a ferrimagnetic multiferroic with a gigantic-induced electrical polarization, and the second one deals with the spin chain oxides of the Sr₄Mn₂CoO₉ type, which have been found to behave as single chain magnets and single ion magnets. These materials that exhibit a potential for applications in the field of memory devices and quantum computation pave the way for future investigations in these systems.