Being a truly two-dimensional crystal, graphene is rippled,
due to both intrinsic thermal instability and stresses created by a
substrate. These ripples result in a pseudomagnetic  gauge field
which effects essentially on the dynamics of charge carriers.
In particular, they can lead to appearance of topologically protected
zero-energy pseudo-Landau levels and to charge inhomogeneity.
Some recent experimental data seem to support a hypothesis that the
pseudomagnetic field in corrugated graphene is the main scattering
factor limiting the electron mobility. External stresses can also induce
the gauge fields leading, in particular, to pseudo-Aharonov-Bohm
effect and pseudo-quantum-Hall effect in zero magnetic field.