More than two million songs have now been bought and downloaded from iTunes Music Store since the launch on 29 April, with more than half of those purchased as part of albums, Apple Computer said.
The online service allows users with Apple Macintosh computers to download songs from a library of more than 200,000 songs for 99 cents (61p) each.
The library features material from all the major record labels, including BMG Entertainment, EMI Group, Sony Music Entertainment, Universal Music Group and Warner Brothers Music Group.
Apple's iTunes received high praise from users for designing an attractive and easy-to-use interface for iTunes.
Users can browse the library, search for songs by title, artist or album and then preview free clips before buying. Following their purchases, users can burn them to an unlimited number of CDs for personal use or download them to any number of Apple iPod digital music players.
iTunes does not rely on subscription fees, and Apple does not emphasise the thorny issue of digital rights management technology. The music also can be streamed to other Macs on a home network or over the internet.
Programmers outside the company have already found ways to harness an iTunes feature, called Rendezvous, that enables Mac users to share downloaded songs with other machines on a Lan or over the internet.
One Apple enthusiast site, www.spymac.com, is offering a music streaming service enabling registered users to browse and search the collections of other iTunes users, then listen to those songs streamed over the internet.
While the service is in its early stages and listening quality is largely dependent on the bandwidth of the individual sharing a song, spymac promises future enhancements to the service.