  We investigate the implications for some nonstandard cosmological models
using data from the first three years of the Supernova Legacy Survey (SNLS3),
assuming a spatially flat universe. A comparison between the constraints from
the SNLS3 and those from other SN Ia samples, such as the ESSENCE, Union2,
SDSS-II and Constitution samples, is given and the effects of different
light-curve fitters are considered. We find that SN Ia with SALT2 or SALT or
SIFTO can give consistent results and the tensions between different data sets
and different light-curve fitters are obvious for fewer-free-parameters models.
At the same time, we also study the constraints from the SNLS3 along with data
from the cosmic microwave background and the baryonic acoustic oscillations
(CMB/BAO), and the latest Hubble parameter versus redshift (H(z)). Using model
selection criteria such as $\chi^2$/dof, GoF, AIC and BIC, we find that, among
all the cosmological models considered here ($\Lambda$CDM, constant $w$,
varying $w$, DGP, modified polytropic Cardassian, and the generalized Chaplygin
gas), the flat DGP is favored by the SNLS3 alone. However, when additional
CMB/BAO or H(z) constraints are included, this is no longer the case, and the
flat $\Lambda$CDM becomes preferred.
