NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY (NIST)
NIST provides tables and graphs to determine the stopping power of various elementary particles in practically any kind of material. ESTAR is for electrons (beta radiation), PSTAR is for protons, and ASTAR is for helium ions (alpha radiation).
Similarly useful are the X-ray mass attenuation coefficients, which give the mass attenuation of all elements up to uranium (Z=92). The energy range covered extends from 1 kev to 100 MeV. Be sure to read the introduction first. Although the mass attenuation of compounds could be calculated by summing over all the constituents, NIST is nice enough to provide data for a few dozen common compounds already.
Well-known to everyone working on atomic physics, NIST also provides the Atomic Spectra Database, which lists levels and transitions of all elements (both neutral and in the first ionization stages).