Over at the Graphic Design blog they posted logos that showcase the emotions of happiness and sadness. The graphic designer can give life to a logo, by adding some subtle or not so subtle imagery to create the emotion they want. It becomes a very powerful logo if you can really feel the emotion in the logo. Does the graphic designer do a good job? It doesn't hurt to have a face to be the face of your company.
http://www.graphicdesignblog.org/smile-frown-logo-designs/ to view the rest of the images.