I am one of those anal people who think the apostrophe should be used correctly. I have been known to go into shops and tell people to fix up their signs (nicely of course). What is the worst case of apostrophe misuse or abuse you have ever seen? Perhaps this site will inspire you.
http://www.nlc.net.au/~brianr/sharon.htm
http://www.nlc.net.au/~brianr/sharon.htm