The NIST XPS database is an absolutely essential tool for tracking down binding energy references and a wealth of other valuable data.

NIST X-ray Photoelectron Spectroscopy Database  

SESSA software is a convenient tool for simulating XPS intensities for simple/complex samples and experimental configurations (such as e.g. synchrotrons).

NIST Database for the Simulation of Electron Spectra for Surface Analysis (SESSA)