BYU ISODISPLACE software: http://stokes.byu.edu/isodisplace.html 

Interactive x-ray diffraction animation:  http://www.physics.byu.edu/faculty/campbell/animations/x-ray_diffraction.html 

Keele University crystallography tutorial:  http://www.keele.ac.uk/depts/ch/resources/xtal/index.html

Oxford Universicy crystallography tutorial:  http://www.chem.ox.ac.uk/icl/heyes/structure_of_solids/Strucsol.html

Pictures of common structures: http://phycomp.technion.ac.il/~ira/types.html 

ILL structure library:  http://icsd.ill.fr/icsd/ 

Mineral structure library:  http://webmineral.com/crystall.shtml

UNM x-ray course: http://epswww.unm.edu/xrd/xrdclass/

Misc IUCr Online resources: http://journals.iucr.org/cww-top/edu.index.html

Pat Woodward's Ohio State crystal symmetry page: http://www.chemistry.ohio-state.edu/~woodward/ch754/symmetry.htm