FEB. 13 | Research firm NPD Group will start publishing an online-subscription gaming quarterly report in an effort to track U.S. revenue and participation in the rapidly growing “massively multiplayer online” industry.

NPD’s Video Game & PC Game Subscriptions Report will include estimates of revenue generated by MMO subscriptions for computer software and games played online, Port Washington, NY-based NPD said in a statement this week.

Online-gaming subscribers have tripled to about 16 million in the past three years, according to Web site Mmogchart.com, while social-networking sites such as News Corp.’s MySpace are jumping into free online gaming in order to secure visitors. Estimates of worldwide revenue from online gaming subscriptions vary widely, though last year the BBC, citing Screen Digest, estimated the market at $1 billion and projected it to grow to $1.5 billion by 2011.

“We wouldn’t be initiating coverage of online subscriptions if we didn’t believe it was a big and growing market,” said Martin Zagorsek, vice president of games and software at NPD. Zagorsek declined to estimate the size of the U.S. market.

Vivendi unit Blizzard Entertainment’s War of Warcraft dominates the online-games subscription market, with a 63% market share, Mmochart.com said. Warcraft, with more than 10 million subscribers, helped Blizzard boost its sales by 58% last year to 814 million euros ($1.19 billion).

UK software maker Jagex’s Runescape and Seoul-based NCsoft’s Lineage and Lineage II each have about 6% of the market, the Web site said.

Meanwhile, MySpace this week started its online gaming page where multiple players can compete in games such as poker and darts. The page stems from a partnership with Oberon Media that was announced last October.

The worldwide gaming audience rose 17% to about 217 million, or almost a third of the world’s Internet users, as of last May, according to ComScore networks. Yahoo! Games attracted the most participants, with a gaming audience of about 53 million, ComScore said.