1. (Most important) Option to disable E-mail functions
Admin can choose from E-mail settings (Admin Control Panel), does board uses automatic E-mail activations, newsletters and stuff... It can be very useful for free webhost users, because most of freehosts do not have PHP sendmail function.
2. (Add-on to Cash Mod) Shop Mod
You can buy things for your profile with points you have earned with your posts. <img>
Link :
http://dowan.org/2005/10/23/shop-mod-261-for-phpbb/