Once the Beatles arrived, Frankie Avalon, whose hit "Venus" was a No. 1 song in 1959, watched as fans ditched syrupy pop for rock 'n' roll.

"I figured that was over," the 66-year-old crooner said about his recording career.

Avalon went on to star in movies of the beach-party genre. His music was relegated to discount bins in record stores and the playlists of oldies stations.

Almost 50 years later, Avalon's work is enjoying a digital renaissance. Thanks to sales on Apple Inc.'s iTunes and other online stores and to music-sharing services like RealNetworks Inc.'s Rhapsody, his royalties have increased a "significant" amount — he wouldn't give details — and he has acquired a new fan base. He tours playing to people whose parents were barely in their teens when his music was popular on transistor radios.

"In the world before digital music, it was very difficult to find my stuff," Avalon said. "Now anybody can find anything."

Sales of albums by contemporary musicians have been falling for years, but deep catalog albums (more than 4 years old) have seen sales soar 104.2 percent from 2005 to 2006. That has been a boon for Avalon and other older artists.

Christina Greco, a 24-year-old art student, is one reason. She was impressed by Avalon's portrayal of Teen Angel in the 1978 movie "Grease" and became a real fan when she learned they both hailed from South Philadelphia.

"I can listen to 'Venus' any time of the day and still be swept away," said Greco, who started a Yahoo group for fans of Avalon and his contemporaries, including Fabian Forte and Bobby Rydell. Greco, who owns many of Avalon's CDs, had an image of the former teen idol printed on her pillowcase. "I've never really been interested in new music," she said.

In the digital age, with a single tune going for 99 cents and a track as accessible as a mouse click, it's easy to mix and match sounds from genres and eras. And playlist-based listening "really benefits those one-hit wonders from bygone days," said Aram Sinnreich, a managing partner at Radar Research in Los Angeles. You probably wouldn't stumble on the Norwegian band a-ha's "Take on Me" in a record store, but there's a chance you would on the Internet.

Businesses are hustling to cash in, buying old songs they hope will come back in vogue. Sacramento-based Digital Music Group Inc. acquired the rights to distribute 335,000 tracks, some that had been owned by Chancellor Records.

Some of the master recordings are stored in a climate-controlled warehouse in North Hollywood. Some, like the 1962 recording "Party Lights" by Claudine Clark, hadn't seen the light of day in decades. The company converts reel-to-reel tapes to digital, salvaging disintegrating and corroded master recordings and preserving them, the company likes to say, forever.

Digital Music Group Chairman Mitch Koulouris, a former Tower Records employee, said the company was bringing new music to listeners when there was less room for CDs on store shelves.

"In many cases, these artists' life work has been locked up in a vault," he said. "Now, they get paid for every single download."