I've got the same question as johnm1019 - I've used FEM for mechanical stress analysis before, but never for electromagnetic stuff - what would the applications of this software be?
http://en.wikipedia.org/wiki/Photonic_crystal
http://ab-initio.mit.edu/wiki/index.php/Meep_Tutorial/Band_d...
You may have heard of optical metamaterials (aka "invisibility cloaks"). They are sometimes made with photonic crystals, but photonic crystals aren't always considered metamaterials. Butterfly wing coloring is a good example.