  We present results for the cross-correlation between the WMAP 1st-year cosmic
microwave background (CMB) anisotropy data and optical galaxy surveys: the APM
and SDSS DR1 catalogs. Our measurement of a positive CMB-galaxy correlation on
large angles (\theta > 4 deg) yields significant detections of the Integrated
Sachs-Wolfe (ISW) effect and provides a new estimate of dark-energy in the
universe, \Omega_\Lambda=0.69-0.86 (2 \sigma range). In addition, the
correlated signal on small angles (\theta<1 deg) reveals the imprint left by
hot intra-cluster gas in the CMB photons: the thermal Sunyaev-Zeldovich (SZ)
effect
