  The anomalous magnetic moment of the muon, $g_\mu-2$, is one of the most
promising observables to identify hints for physics beyond the Standard Model.
QCD contributions are currently responsible for the largest fraction of the
overall theoretical uncertainty in $g_\mu-2$. The possibility to determine
these hadronic contributions from first principles through lattice QCD
calculations has triggered a number of recent studies. Recent proposals to
improve the accuracy of lattice determinations are reported. We present an
update of our studies of the leading-order hadronic contribution to $g_\mu-2$
with improved Wilson fermions.
