Three music subscription services, that is. Three services where you can download all the tunes you want for a monthly fee and then transfer the music to certain portable devices. Of course, you don’t actually own the music. Instead, you rent it. Once you stop paying, the music stops playing.

The latest company to hang out their “music for rent” shingle is Yahoo, which announced Yahoo Music Unlimited, a plan where the Web giant undercuts its competition in the music leasing biz, namely Napster and RealNetworks, by more than 60 percent.

Renting music from Yahoo will cost you $6.99 per month or $60 for an annual subscription. By comparison, both RealNetworks and Napster charge $14.95 per month and $180 annually.

However, if you’re interested in taking Yahoo up on its bargain-basement subscription prices, you better act soon. Nothing is forever, and Yahoo is making no guarantees that the $60 per year pricing plan is here to stay, leading many industry watchers to speculate that the offer is designed to snag new users, and that the company’s rental prices might eventually end up similar to the competition’s.

Like Napster and RealNetworks, tracks rented from Yahoo Music Unlimited cannot be burned onto CDs unless you actually purchase the track. However, Yahoo is selling songs for 79 cents each, 20 pennies less than what Apple charges for tracks purchased from its iTunes Music Store.

While there are many personal music players on the market that will play music from all three rental services, neither the leased tracks or purchased tracks will play on America’s number one digital player, the iPod.

In fact, the whole media buzz about Yahoo’s new service seemed to focus on what it might mean for Apple, with various “experts” expounding on whether Apple would eventually adopt a similar service.

“Yahoo Strikes At Apple’s Core” read the headline in the May 11th edition of the San Francisco Chronicle, while The Wall Street Journal speculated that music rental services “could eventually pressure [Apple] to release its own offering.”

Meanwhile, investors apparently like what they’re hearing about Yahoo Music Unlimited. Yahoo’s stock gained 82 cents, or 2.4 percent on Nasdaq on May 11th for a closing price of $34.88. Napster dropped $1.70, or 26.8 percent to close at $4.65. RealNetworks slipped $1.54, or 21.1 percent, to close at $5.76. Even Apple felt the power of Yahoo’s yodel by losing 81 cents, or 2.2 percent, to finish that day at $35.61.

Yahoo’s entry into the music rental biz increased speculation that renting music might be the digital model of the future. After all, it doesn’t matter whether you rent or own as long as you can play your favorite tune whenever you want, wherever you want. Should you care that you can’t burn rentals onto CDs? Probably not. Not when you can just jack your personal player into your stereo.

Or as Dave Goldberg, general manager of Yahoo’s music division, said upon the launch of Yahoo Music Unlimited: “This is all about expanding the market. We are convinced this is the way you should be listening to your music.”