It has long been the digital music's game poorly kept secret, residing in a legal gray area somewhere in between legal download services like iTunes and the illegal peer-to-peer (P2P) networks.

But AllofMP3.com, the Russian download site that charges as little as 11 cents per song compared to the 99-cent standard established by iTunes, is playing second fiddle only to iTunes in the UK, according to market research firm XTN Data.

XTN based its data on a regular poll of 1,000 British digital music buyers rather than the industry-supplied sales figures on which most digital music reports rely.

The firm found that iTunes accounted for 44 percent of music download purchases in the UK last month, while AllofMP3 came in second at 14 percent. Napster, Wippit, and MSN rounded out the top five, at eight percent, six percent, and six percent, respectively.

The gray area in which AllofMP3 exists comes because it claims legality through a license agreement between its parent company and the Russian Multimedia and Internet Society, as well as the Rightholders Federation for Collective Copyright Management of Works Used Interactively.

AllofMP3 claims that the license agreements permit the company to sell any song in any format without having to obtain the permission of copyright holders like the major labels or music publishers. The site sells digital music at several levels of compression and fidelity, charging more for higher-fidelity songs.

As a result, AllofMP3's inventory includes the latest and most popular digital releases on the market, including Tool's 10,000 Days and Gnarls Barkley's St. Elsewhere.

According to The Register, the International Federation of the Phonographic Industry (IFPI) is keeping its eye on the site but has yet to take any direct action against it. Last year, it made a formal complaint to the Russian authorities, only to see Moscow prosecutors drop the case because a loophole in the country's copyright laws, which are geared toward the protection of content of physical media.