I know mostly Batman trivia, a lot of which came from IMDB:
The following auditiond for Nolan's Batman to be Batman/Bruce Wayne: Christian Bale, Joshua Jackson, Eion Bailey, Hugh Dancy, Billy Crudup, Cillian Murphy, Henry Cavill and Jake Gyllenhaal.
Writer David S. Goyer wanted Gyllenhaal to play the role, but then saw Bale and changed his mind.
Ashton Kutcher was strongly considered for the role of Bruce Wayne/Batman also.
Marilyn Manson was considered for Scarecrow in Batman Begins.
Chris Cooper turned down the role of Jim Gordon in Batman Begins. Also considered were Dennis Quaid and Kurt Russel.
Viggo Mortensen turned down the role of Ras Al Ghul in Batman Begins.
Anthony Hopkins turned down the role of Alfred in Batman Begins.
Lawrence Fishburne was considered for Lucious Fox in Batman Begins.