Re: artists' ?
Actually, it's only used in the plural possessive form. So, "I'm getting my class's syllabus," is correct, because 'class' is singular. But, "I need to know all the special cases' exceptions," is also right because 'cases' is plural (although the sentence itself is of questionable English...;-) ).
jb4
"We continue to live in a world where all our know-how is locked into binary files in an unknown format. If our documents are our corporate memory, Microsoft still has us all condemned to Alzheimer's."
Simon Phipps, SUN Microsystems