  We calculate adiabatic charge and spin pumping through a serial double
quantum dot with strong Coulomb interaction, coupled to normal metal or
ferromagnetic contacts. We use a real-time diagrammatic approach in the regime
of weak coupling to the reservoirs. In the case of weak interdot tunnel
coupling we investigate the influence of tunnel-induced renormalization effects
due to charge fluctuations on the pumped charge and spin. We show that
tunneling through thermally excited states can play an important role in the
strong interdot coupling regime. In particular, for ferromagnetic contacts,
both effects enable the generation of pure spin currents. Furthermore they can
lead to an inverted spin-valve effect or even to the inversion of the transport
direction going along with a diverging tunneling magneto-resistance.
