Growing between 40,000 and 95,000 fans a day over the past week, Toys”R”Us has become the fastest growing brand on Facebook. The company, which recently released its “Big Book” catalog of toys on its Facebook Page, has been experiencing tremendous growth in the past few days. While we don’t know the exact reason for the growth (we’d assume it’s the result of an ad campaign), there are a number of features within the company’s Facebook Page which drives new fans.

With Black Friday impending, Toys”R”Us has developed a custom Black Friday Preview application which lets Facebook fans find out what deals are available. Also, in order to drive new fans, the company is limiting the visibility of some Facebook Page tabs to only fans. On the development side, rather than using the fb:visible-to-connection FBML tag to limit visibility to fans only, ContextOptional, who helped develop the page, has appeared to use a simple custom application to verify whether a user is a fan and if not, force them to become one.

While we have no way to verify whether or not this method has been effective, it’s clear that the company has effectively grown its fan base. By the end of today, there’s a good chance Toys”R”Us will surpass 400,000 fans, which is no easy feat, unless of course you use the “pay per fan” model that appears to be increasingly popular among large brands looking to build their Facebook presence.

While the volume of new fans each day appears to be slowing, Toys”R”Us is now among the some of the top brands across Facebook. Do you think most of this growth is a result of the company buying fans or do you think the company naturally jumped by almost 90,000 fans in a day?