Reverberation mapping is a proven method for obtaining black hole masses and exploits time lags between continuum and broad line light curves. We focus on the observed interband continuum – continuum delays and interpret these as thermal reprocessing of a central irradiating point source centered on, and illuminating, a geometrically flat, optically thick accretion disc. In this model, longer wavelengths are emitted from cooler regions at larger radii within the disc and the distribution of time lags (the response function) is sensitive not only to these wavelength effects, but also to the disc inclination, accretion rate and temperature radius law. I will introduce a novel Bayesian MCMC code (CREAM) and present fits to sub-day cadence light curves of NGC 5548 obtained by the Space Telescope Optical Reverberation Mapping Campaign (STORM). I will also describe our current efforts on developing the above techniques to use Quasar accretion disks as standard candles for cosmology.