These are interesting. Some related things that came into mind are e.g. prices that end in 9 might increase sales (http://link.springer.com/article/10.1023%2FA%

These are interesting. Some related things that came into mind are e.g. prices that end in 9 might increase sales (http://link.springer.com/article/10.1023%2FA%3A1023581927405 http://link.springer.com/article/10.1023%2FA%3A1023581927405). Or a waiter bringing mints when they give diners their checks increases tips significantly (http://www.helpscout.net/blog/the-psychology-of-personalization-how-waiters-increased-tips-by-23-percent-without-changing-service/ http://www.helpscout.net/blog/the-psychology-of-personalizat...).