Livephish.com offers a rare service: soundboard-quality downloads of performances within two days of the concert. Fans pay $9.95 for MP3s or $12.95 for a computer file format where no sound quality is lost during compression.

In the first four months after the site's launch on New Year's Eve 2002, the service generated $1 million, said Brad Serling, whose company runs the site as a joint venture with the band.

"It's beyond our expectations," Serling said. "It's been profitable from day one."

Like the Grateful Dead, Phish has always encouraged fans to record their performances. Likewise, their performances vary widely from night to night, and the band has spawned a subculture of hard-core fans who began trading recordings long before Napster.

Since Livephish's launch, many of the band's young, digitally adept fans have proved willing to pay for an improved version of what's already available at no cost. Sound quality is better, and fans appreciate the convenience of being able to access the equivalent of three CDs of music just 48 hours after the show.

During an end-of-tour festival last weekend that drew an estimated 70,000 fans to the remote town of Limestone, a long line of concertgoers snaked outside a white tent called the House of Live Phish. Fans used Apple iMacs to make their own free CDs from a menu of three or four songs performed at each of the band's concert stops this year.

Some burned their CDs, then jumped right back in line. And fans offered rave reviews of the Livephish service.

"To release it two days later in soundboard quality is the ultimate treat for a fan," said Brian O'Neal, 28, of Nashua, N.H. "I think that could be the greatest thing a jam band ever did."

Eighty percent of each concert's sales at Livephish.com come within a week of the show, according to Serling.

"This is totally new," gushed Bret Berman of Boulder, Colo. "And I think a lot of bands are going to start doing it."

Some other bands are tapping into the market for their live performances. Pearl Jam has begun releasing CDs of each of its concerts, and New York-based Rockslide sells CDs of live shows by a number of lesser-known bands.

The biggest hurdle is likely to be record label resistance, said Josh Bernoff, an analyst at Forrester Research in Cambridge, Mass.

Phish has an unusual contract with Elektra Records that gives the band the right to let fans record its live shows. Elektra, owned by AOL Time Warner Inc., gets a share of profits from Livephish.com, Serling said.