I've started an [Atmospheric Chemistry Graphics Library|http://eo.ucar.edu/staff/rrussell/atmosphere/atmospheric_chemistry/atmospheric_chemistry_graphics_library.html] web page with images of various representations (space-filling models, ball-and-stick models, etc.) of molecules relevant to atmospheric science (carbon dioxide, methane, molecular nitrogen and oxygent, etc.) and of reactions important in atmospheric chemistry. I created some of these graphics, some were made by COMET, and some are on Wikipedia.