  We describe a new method for extracting gravitational wave signals from
pulsar timing data. We show that any gravitational wave signal can be
decomposed into an orthogonal set of sky maps, with the number of maps equal to
the number of pulsars in the timing array. These maps may be used as a basis to
construct gravitational wave templates for any type of source, including
collections of point sources. A variant of the standard Hellings-Downs
correlation analysis is recovered for statistically isotropic signals. The
template based approach allows us to probe potential anisotropies in the signal
and produce maps of the gravitational wave sky.
