Amazon.com Inc. today added another feature to its Prime free-two-day-shipping-and-more program. Members can now stream or download more than 1 million digital songs through Prime Music.

A Prime membership costs $99 per year, although Amazon gives discounted or free memberships to students and other groups. Besides the shipping benefit on some 20 million Prime-eligible products, members also receive sweeteners such as access to “tens of thousands” of movies and TV shows through Prime Instant Video and can borrow electronic versions of some 500,000 books, Amazon says.

Prime Music comes with no ads and can be listened to on Kindle Fire HD/HDX devices or through the Amazon Music app for Apple Inc. or Android devices.

“Prime Music is the latest great addition for Prime members and we think they’re going to love it,” says CEO Jeff Bezos. Artists include Baby Boomer demi-gods The Doors, former 70s shredders and current movie soundtrack ballad kings Aerosmith and electronic dance darlings Daft Punk.

At this week’s Internet Retailer Conference and Exhibition in Chicago, Colin Sebastian, a longtime Amazon observer and e-commerce analyst who works for Robert W. Baird and Co., estimated that Prime had 25 million paid members though perhaps as many as 50 million users, given that households can share accounts. Still, Amazon has made only an estimated 10% of its products available for Prime shipping, he said. “It’s still the early days for Prime.”