After a day of research, I wanted to post some tips for authors looking to market their books.
The website ContactAnyCelebrity.com has thousands of actors, producers, athletes, musicians - you name it! They currently offer a one week trial subscription for $1 that is well worth looking into if you want endorsements for your book.
I also recommend having a list of celebrities you wish to contact before going to that site, too. Find celebrities that would be interested in the subject of your book, grew up in the location of your story or went to college there, or that support your charity cause. Do a google search, plus visit IMDB.com (Internet Movie Data Base) and search through the bios posted on that site.
As always, best to think about these things before you write your book! Just like product placement and movie tie-ins are vitally important, you need these in your book, too!