  To investigate the possibility of charge order and superconductivity in a
doped two-dimensional triangular lattice, we study the extended Hubbard model
with variational Monte Carlo method. At n=2/3, a commensurate filling for a
triangular lattice, it is shown that the nearest-neighbor Coulomb interaction V
induces honeycomb-type charge order and antiferromagnetic spin order at U>10t.
We also discuss the possibility of superconductivity induced by charge
fluctuation and the relation to the superconductivity in
Na_{0.35}CoO_{2}1.3H_{2}O and theta-type organic condoctors.
