  Cross-correlation between the CMB and large-scale structure is a powerful
probe of dark-energy and gravity on the largest physical scales. We introduce a
novel estimator, the CMB-velocity correlation, that has most of his power on
large scales and that, at low redshift, delivers up to factor of two higher
signal-to-noise ratio than the recently detected CMB-dark matter density
correlation expected from the Integrated Sachs-Wolfe effect. We propose to use
a combination of peculiar velocities measured from supernovae type Ia and
kinetic Sunyaev-Zeldovich cluster surveys to reveal this signal and forecast
dark-energy constraints that can be achieved with future surveys. We stress
that low redshift peculiar velocity measurements should be exploited with
complementary deeper large-scale structure surveys for precision cosmology.
