If streaming music on your computer for free appeals to you, consider this: in the near future, you might be able to do the same thing on your smartphone or other portable device.

A growing number of companies are rushing to offer free streaming music on their websites. Just type in the name of a song and it starts playing. No need to buy it beforehand or rip it from your CD library.

The idea is fine as long as you're attached to a computer. The next frontier, however, is making that same music widely available on handheld devices like the iPhone and BlackBerry.

"Most streaming media is consumed online in a browser, whereas we believe in just a few short years from now it will be in the mobile environment," said Andy Whatley, president of American Media Services Interactive, which has developed a streaming music site called TheRadio.com (www.theradio.com). It's still in beta mode and the song selection so far is pretty slim, but other sites offer millions of songs.

Last.fm (www.last.fm/home) has been around for years. Type in Coldplay and you'll hear not only songs from the British pop stars, but also from similar acts such as Snow Patrol and Keane. The aim is to let listeners discover new music and interact with friends by sharing songs and looking at each other's playlists.

Jango (www.jango.com) allows you to create and edit playlists for your own personalized radio station. You can control how often each song plays, depending on how much you like it. There's also a social-networking aspect to the site, allowing you to send messages to friends, tune in to their station, or make new friends who register similar musical tastes.

These sites, as well as a handful of similar ones, require listeners to use an Internet browser. What has Whatley and others excited is the idea of letting music fans take that technology to their mobile device.

"We believe what will happen over time is that ... it becomes adaptive, so that the listener gets the notion of `I want media my way -- how I want it, when I want it,"' said Whatley.

Pandora (www.pandora.com) has started moving in that direction. It has already given away two million downloads of its free application for the iPhone, and has just released a version for a few Windows-based mobile devices.

There are still a few hurdles to clear before free music-on-the-go becomes widespread. For one thing, music companies have been fighting for higher royalties for each song played by an Internet radio station or streaming music service.

The U.S. Copyright Royalty Board raised song royalties last year, prompting companies like Yahoo to scale back their music services. One industry group said royalties could eat up as much as 70 per cent of the revenues generated by Internet radio stations.

There are also licensing restrictions governing where songs can be streamed. Canadians are blocked from using Pandora, which states on its website: "Due to licensing constraints, we can no longer allow access to Pandora for listeners located outside of the U.S."

Will it make money?

There is as well the question of how these sites can ensure long-term profitability. Most offer music for free and rely on banner ads for revenue. But those ads don't have nearly the same effect on a mobile device, which a consumer may not even be looking at while walking down the street listening to music.

Whatley thinks a subscription model might be workable. For a monthly fee, users would be able to listen to virtually any song they want without being subjected to ads. But many music fans have been cool to downloading sites that require a monthly fee.

Rob Warren, a professor at the Asper School of Business at the University of Manitoba, thinks the time may be ripe for subscription services, because more people have become comfortable with Internet transactions.

"(Older) subscription models weren't very well developed, and people were leery of them -- like, `Will the company be around long enough for me to realize my subscription,"' Warren said.

"I think that that's changed now."

But a subscription-based business model will inevitably have to compete with ad-based services that are free to the consumer. There are also variations such as Seeqpod -- not a licensed music service, but an MP3 search engine that combs the web for songs that can be streamed. Seeqpod has raised the ire of record labels, who say many of the MP3s on the web are posted illicitly, providing no compensation to the artist or copyright-holder.

Seeqpod recently launched a Windows mobile application which it says will allow users to find and play virtually any song on their handheld device, in exchange for a one-time payment of about US$10.