In an effort to attract more subscribers to its digital music service, Napster on Monday launched an ad-supported offering that allows users to listen to over two million tracks free of charge. The songs are streamed in low-quality audio and can only be heard five times each, without having to submit any credit card information. However, after the five times customers will need to either buy the title or sign up for a monthly subscription to listen to that song. Each track can be purchased for 99 cents.

Napster rival RealNetworks' Rhapsody service offers a similar free option, but it is limited to 25 tracks per month. Napster offers a plan for $9.95 a month that offers its users unlimited online listening, or $14.95 for a service that lets users transfer songs to certain portable devices, except iPod.

Napster on Monday also announced two new features, including NapsterLinks, which allows customers to add links to free Napster music to e-mail messages, instant messages and Web sites. NapsterLinks are URLs that link to specific songs, albums or artist in the Napster.com catalog, and the URLs are created using a free tool, the company said.

Also announced is the Narchive, a public music archive where customers will be encouraged to contribute to an ever-expanding audio and visual dialog of the "people's history of music," the company said. Customers will be encouraged to add personal stories and photos about music in personal entries at the Narchive. Using NapsterLinks, they will be able to link to the music and artists they write about.

The Narchive will be available in a beta release soon, Napster said.