One of the fun stories about archaea that many people may not know is there is not a single species known to be pathogenic (this is not to say there are not any, but we know of a lot of them and none are pathogenic), while with bacteria there are a great number which are harmful to us. I think an interesting post could be made discussing these guys a bit with people, a whole domain of life that most people do not even know exist!
http://www.ncbi.nlm.nih.gov/pubmed/14579252
http://onlinelibrary.wiley.com/doi/10.1002/bies.201000091/full