Think "autograph" and images of crowds of screaming fans mobbing celebrities comes to mind, or maybe a more organized event with people lining up in droves and the celebrity sitting behind a table. Either way the end result is the same: a lot of signatures leaving with a lot of satisfied fans. And that's great for all those people who now have a souvenir to cherish, but not so much for collectors. In order for a signature to be worth a lot in terms of money it has to be fairly rare.

He may have done a lot of writing, but with only 6 of them in existence William Shakespeare's signature is one of the rarest of all and is valued somewhere around $3 million dollars. And as far as present-day celebrities go it's a harder call to make, but this past year Will Ferrell topped the list of worst celebrity signers (which would, in theory, make his John Hancock just a little more rare).

Celebrities spend a lot of time signing autographs, but besides personal value the ones that really end up being worth lots of cold hard cash are the rarest ones. In today's day and age it's hard to get through a single day sometimes without signing for a credit card purchase or something else, but hundreds of years ago things were different. Even for somebody who spent most of his time with a quill in his hand.

For all the writing William Shakespeare did he apparently didn't sign his name very often. Today there are only six of the playwright's known authenticated signatures in existence, which helps make his John Hancock one of the most valuable in the world. One can be found on a conveyance for a house in London, one on a legal deposition, one on his mortgage documents, and three in his will. And any one of those is worth $3 million, seriously.