A Facebook page for a business or organization can never have too many fans and visitors.
Woobox lets you create promotions that encourage sharing and more exposure for your brand through coupons, sweepstakes, polls, group deals, custom tabs, and more. Its FriendGate feature requires visitors to persuade a certain number of their friends to like your page before they can receive an offer. It also has several different ways of rewarding sweepstakes participants who get their friends to enter.
Woobox is available as a free version that gives you a custom tab and coupons; for $29 a month, you get everything Woobox offers.