Solid State Stoichiometry Online
The page has JSmol structures for unic cells including cubic, body centered cubic, and face centered cubic unit cells as well as for CsCl, Ni3Al, Cu2O, NaCl, CaF2, ZnS, diamond, Li3Bi, NaTl, NiAl and ReO3. The advanced page also has triclinic, monoclinic, hexagonal, orthorhombic, and tetragonal cells with all possible centering.