Here are some funny links:
These are letters people took the time to write to complain about other people's vanity plates in Washington:
http://www.thesmokinggun.com/archive/washplates1.html
Here are letters to some other state that are pretty funny also:
http://www.thesmokinggun.com/archive/wiscplates1.html
Here is a letter where a guy tried to explain his plates GOTMILF:
http://www.thesmokinggun.com/archive/0721041plate5.html