Reverberation mapping is a well-established method for measuring the masses of super-massive black holes in AGN.  This technique can also be used to probe the temperature structure of AGN accretion disks by measuring time-delays between broad-band continuum light curves. I will discuss the detection of continuum lags in NGC 5548 (from the AGN STORM project) and implications for the accretion disk. I will also present evidence for continuum lags in two other AGN for which we recently measured black hole masses from continuum-Hbeta reverberations. The mass measurements allow us to compare the continuum lags to predictions from standard thin disk theory, and our results indicate that the accretion disks are larger than the simplest expectations.