1. Mr. Poe refers to a You-Know-Who in his letter to his sister Elenora - "P.P.S. Have you heard from You-Know-Who?"
2. Count Olaf refers to a You-Know-Who in The Hostile Hospital - "We've got to find the Snicket file as soon as possible, before You-Know-Who does."
3. While writing about Alexander the Great, Snicket calls him "You-Know-Who the Great" - pg. 200, TWW.
Can anybody think of any other references to a You-Know-Who, or is it possible we're going to see a character named Alexander in the next two books? Or am I going overboard with the theories? ;)