  We calculate the pressure (p), the energy density (\epsilon) and the baryon
density (n_B) of QCD at finite temperatures (T) and chemical potentials (\mu).
The recently proposed overlap improving multi-parameter reweighting technique
is used to determine observables at nonvanishing chemical potentials. Our
results are obtained by studying n_f=2+1 dynamical staggered quarks with
semi-realistic masses on N_t=4 lattices.
