There’s a new stocking stuffer for the social gamer on your holiday shopping list: Facebook Credits.

Already available at Target stores, the social networking site is set to offer the credits -– which can be used for in-game purchases in games like FarmVille –- at Walmart and Best Buy too. Walmart will offer $5, $10 and $25 versions of the gift cards, while Best Buy will sell them in denominations of $10, $25 and $50.

A Facebook spokesperson tells Mashable that, “As we approach the holiday gift-giving season, we’re happy to expand the availability of Facebook Credits gift cards to Walmart and Best Buy. More than 200 games and applications accept Facebook Credits, giving people a fun, convenient and secure way to buy premium items, and making Credits gift cards a unique gift for the holidays.”

The soon to be ubiquitous nature of Facebook Credits gift cards speaks to the momentum behind the rapidly growing social games and virtual goods business, which is expected to grow to $6 billion by 2013.

Gift cards help make that currency available to everyone — not just those with credit cards or PayPal accounts — and we imagine we’ll continue seeing them hit the “impulse purchase” section of many a chain store.