  The MILC collaboration has been performing realistic simulations of full QCD
with 2+1 flavors of improved staggered quarks. Our simulations allow for
controlled continuum and chiral extrapolations. I present results for the light
pseudoscalar sector: masses and decay constants, quark masses and
Gasser-Leutwyler low-energy constants. In addition I will present some results
for heavy-light mesons, decay constants and semileptonic form factors, obtained
in collaboration with the HPQCD and Fermilab lattice collaborations. Such
calculations will help in the extraction of CKM matrix elements from
experimental measurements.
