Sales of virtual goods and prepaid game cards grew steeply on Black Friday and the Thanksgiving weekend compared to a year ago. That means that online gamers are increasingly embracing opportunities to spend their real money on virtual goods for online games.

According to virtual goods company PlaySpan, sales of Ultimate Game Card prepaid cards for online games were up 48 percent on Black Friday compared to a year ago. Sales were also up 69 percent from the week before Black Friday. PlaySpan has a good view of the business because it operates a platform used by a lot of big players in the industry who want to make money from online games.

PlaySpan sells the Ultimate Game Card prepaid online game cards, which can be used in more than 1,000 online games, in more than 50,000 retail locations. Users buy the cards and enter a code online. They can then get virtual currency to spend in their favorite online games. Since the Ultimate Game Card is used in so many games, its sales are a good proxy for the health of the online game market, said PlaySpan chief executive Karl Mehta.

The Santa Clara, Calif.-based company also operates a virtual goods platform that game publishers use to add virtual transactions to their games. PlaySpan also runs the PlaySpan Marketplace, a site where online gamers can shop for virtual goods in a wide variety of games.

The PlaySpan Marketplace saw a 56 percent sales increase on Black Friday compared to a year ago. For the entire four-day holiday period, sales were up 19 percent from a year ago on the marketplace. By comparison, the console video game market in the U.S. is down 8 percent year to date, according to market researcher NPD.

Virtual good sales are still fairly small in the grand scheme of the game business. The virtual goods business in the U.S. is expected to hit $1.6 billion in 2010, according to Inside Network. That’s substantially less than $20 billion expected for the console game business in the U.S. But the growth rates are worth noting.