Farmville fans rejoice as your painfully addicting fanciful Facebook game has gotten a new lease on life. The social networking giant anounced today that it has signed a five year deal with Zynga that will keep the gaming company firmly entrenched in Facebook. In a move that will help solidify Facebook’s form of currency, part of the deal requires Zynga to adopt Facebook’s proprietary credits system for its in-game cash transactions, starting first with a few select games and expanding to Zynga’s other games in the future. As for Facebook itself, not only is the site becoming more influential, but it’s also growing in size with the number of registered and non-registered visitors ballooning to an estimated 516 million in the month of April alone. According to Comscore, this figure places Facebook firmly in fourth place worldwide with only Yahoo, Microsoft, and Google ahead of the gargantuan social network.