While this site is also a commercial site (selling Theo's periodic tables and book, etc.) it is a wonderful resource of pictures of elements and their compounds, and "real life" uses of elements (such as a gamma ray imaging of the skeleton for Tc, a hard drive for B, and sushi for Hg!). It is also a source of movies of reactions of the elements, including some pretty impressive ones for the alkali metals and the thermite reaction. It also provides easy access to his chemistry column for Popular Science magazine.

This website provides access to many formulations of the periodic table over time. I think that looking at the various representations of the table would provide an excellent way to discuss periodic trends.

This list was compiled by Mark R. Leach and is part of his free resource, The Chemogenesis web book.

The University of Oklahoma has put together a nice website on Crystallography which includes a standard introduction to crystallography & crystal symmetry. I also like some of the features that you don't normally come across including evaluating crystal structures and twinning.

At the end of my inorganic course, I teach several "cool" spectroscopic techniques that inorganic chemists use.  These techniques are discussed within the context of bioinorganic chemistry, and I typically cover EXAFS/XANES, X-ray crystallography, EPR and Mössbauer.  

This website introduces (or reviews) Fourier Transforms in a neat graphical way, but most importantly, illustrates the phase problem.  Given the intensities from your crystal and the phases from your model, the phases are more important!  Which is too bad, as we don't have ready access to that information.

At the end of my inorganic course, I teach several "cool" analytical techniques that inorganic chemists use.  These techniques are discussed within the context of bioinorganic chemistry, and I typically cover EXAFS/XANES, X-ray crystallography, EPR and Mössbauer.  I provide this website to the students as supplemental reading material for X-ray crystallography, which is not typically covered in depth in an introductory inorganic text.  The first link is the main website, but I usually only focus on the 2^nd and 3^rd links which covering the experimental setup for an X-ra

The Interdisciplinary Education Group at the University of Wisconsin Madison Materials Research Science and Engineering Center (MRSEC) has a fabulous website with a wide variety of great resources for teaching about materials and the nanoworld at all levels.  A favorite "corner" of this website that I refer to a lot in my own teaching is the library of so-called Resource Slides on a variety of topics.  These Resource Slides are divided up into 36 topical Slide Shows and include wonderful graphics to use in class presentations.   Slide Shows include: