I had to think over some of the books for the three extra dice rolls, but with the help of BrokenTune I managed to choose a book for all the squares:
Frontierland 1: The Thin Man by Dashiel Hammett. I´m not completely satisfied with this choice for this square (because it´s not a western), but I really want to read this book and the title starts with a t.
Frontierland 4: Poirot Investigates by Agatha Christie. I have such a huge stack of Christie´s at home, I really need to read more of her books.
Main Street 10: To Kill a Mockingbird by Harper Lee. BrokenTune recommended this book to me and it´s been on my to-read list for ages. And it´s about time that I read it.