2. Deezer: Deezer offers users free and legal streaming music while sharing advertising revenue with artists and rights owners. The site launched with a Sony BMG partnership and signed a Universal Music deal in 2008. Users can share their favorite music by connecting with friends within the social network, or embedding playlists in 3rd party sites.

3. Spotify: Heralded as one of the best music streaming experiences on the market, Spotify is only available in the UK, Sweden, Norway, Spain, France and Finland. TechDigest TV uploaded a fantastic looking preview of Spotify's much anticipated iPhone app.

4. Tunerec: Swedish company Tunerec allows users to create music libraries and playlists from recorded radio play. Because libraries are taken from recorded music, it takes a while to populate playlists; however, according to RWW's initial review by Frederic Lardinois, the service is worth the wait.

5. Last.FM: If you haven't heard of Last.FM, you've probably been living under a rock. The site offers users the ability to create radio stations and stream them complete with AudioScrobbler-powered recommendations.

6. Pandora: To the user, Pandora and Last.FM are similar recommendation-based radio services; however, where AudioScrobbler makes statistical inferences, Pandora's recommendations are determined by the Music Genome Project's 400 distinct musical characteristics.

7. Slacker: Slacker is another popular radio recommendation service. Users input tracks and receive recommendations. Slacker first launched with custom mobile hardware and has since expanded onto other mobile devices.

8. The Hype Machine: This is a fantastic service for those willing to leave music selection to the experts. Like other sites, this one allows listeners to search for music and stream playlists; however, the files on the site are actually streamed from the blogs of top labels, DJs, promoters and music start ups.

9. Blip.fm: Blip.fm is another site where music lovers can access millions of streaming songs. Members receive their own station and the ability to share station programming responsibilities with friends. The site also offers integration with blogs, Twitter, FriendFeed and Last.fm. The act of blipping refers to the act of linking to a song and attaching a 150 character comment to it.

10. MOG: MOG is a music blog network that encompasses more than 300 blog posts per week. The site offers an in-depth look at new artists and includes music recommendations, videos and streaming audio clips. A good place to start with this service is to play audio from it's Recently Popular Posts page.

11. Lala: Lala also offers users a playable web browser interface. The service contains 7 million free online songs and the ability to purchase additional web songs at 10 cents each or downloadable MP3's for 80 cents and up each.

12. Imeem: Imeem is considered "the new social mixtape". The streaming music site allows users to create playlists and share them across the web. RWW recently covered Imeem's iPhone and Android launch.

13. SoundCloud: SoundCloud also allows users to upload tracks and share them via the cloud. Listeners receive shared files via an email-style interface. From there, they can choose to either play the music from the site or download the tracks they've received from friends.

14. 8Tracks: This service lets users upload 8 tracks as a playlist and share the playlist with friends. This service is essentially what Muxtape used to be.

15. Muxtape: Muxtape has transformed from one of the early mixtape-style music sites (users uploaded and shared playlists) to a directory of bands. It remains a great place to discover indie bands.

16. Project Playlist: Project Playlist indexes music from across the web. Again, users create playlists and share links to music files with their friends. Reviewers see this as one of the best music search engines in existence.

17. Skreemr: Skreemr is also a search engine and music indexing site. It claims to offer users access to "6 million mp3 files from over 100,000 web sites".

18. Fizy: Similar to the now defunct Seeqpod, Fizy is an extremely bare bones approach to streaming music with a simple search bar. Like Seeqpod, the site offers speedy music video results and audio results, and unfortunately, legally questionable content. Perhaps the site's recent acquisition will change that.

On the Horizon: Microsoft is set to launch a streaming music site at the end of July. For more info on this project check out our coverage.

The service now also shows display ads on its website, which, to be honest, don't seem to fit into the general design of the site and look like they were just added for the sake of it.

In the Bloomberg interview, Westergreen also acknowledged that Pandora's struggle with the music industry to negotiate royalty rates could still stop the company from becoming profitable, though Westergreen also said that he is optimistic that these negotiations will come to a positive conclusion for Pandora.

Upload with AIR - Play Over the Air

You upload your music with an Adobe AIR app which allows you to upload songs directly from your hard-drive, but also has a convenient option that lets you browse your iTunes library to pick songs you want to transfer to imeem. In our tests those uploads worked just as expected and went relatively fast. The sounds quality was also surprisingly good.

Similar to the iPhone apps from Pandora, Last.fm, and and Slacker Radio, you can also easily create custom radio stations, though the functions here feel a bit limited compared to the options that imeem competitors now offer.

Like its competitors, the app suffers from the fact that it can't play in the background on the iPhone. Sadly, imeem also doesn't remember where it left off after you exit the app.

Pricing

You can store up to 100 songs, 10 videos, and an unlimited amount of photos on imeem for free. For $30 a year, you can upload up to 1000 songs and 100 videos, and $100 a year buys you storage for 20,000 songs and 500 videos.

Alternatives

We are also big fans of Lala, which allows you to listen to all of your songs online without any restrictions. Sadly, though, Lala does not offer a mobile application.

If you want full access to the music on your desktop while on the go, Simplify Music 2.0 also does a great job at streaming your collection over WiFi, Edge, and 3G. One of the nice features of the Simplify Music app (iTunes link) is that it gives users easy access to lyrics and artist biographies. Imeem only provides access to artist biographies.

Verdict

Given the quality of the apps that imeem's competitors have released, this app still has a bit to go before it can fulfill all of its promises. However, if you are looking for a simple way to expand the capacity of your iPhone or Android phone then imeem might be worth a look, especially if you don't keep your music on a home server where you can easily access it with Simplify Media or Simplify Music.

Overall, Slacker feels a lot like satellite radio, which is probably no surprise, given that XM Radio's co-founder Lon Levin is Slacker's Senior Advisor.

With regards to its user interface, every Pandora and Last.fm user will feel right at home. One nice addition to Slacker, though, is the ability to see which songs will play next.

Customization

One advantage of Slacker over its competitors is that it gives you more options to directly customize your stations. You can direct it to play songs from different decades, and decide if you want it to mostly play hits or also more obscure songs.

Competition

Slacker's reviews and biographies can't quite compete with the depth of information offered by the Last.fm app, which can also display tour dates. Slacker also doesn't feature any of the social networking functions that have made Last.fm so popular.

Just like its competitors, Slacker only allows you to skip six songs per station every hour. Unlike Pandora and Last.fm, however, Slacker does play 30 second radio ads after every fifth song. For $3.99 a month, however, you can buy a premium membership that lets you skip songs as often as you want and which removes the advertising from your stream.

Like all the other streaming music apps on the iPhone, Slacker can't play in the background while you surf the web or read your email. This, of course, is a limitation that Apple has put on its developers, even though Apple's own music player on the iPhone does this without causing any problems.

Verdict

Even though Slacker Radio is very similar to the Last.fm and Pandora app, we think it is definitely worth a try. Whether you prefer one over the other will depend on how happy you are with the music recommendations it gives and how important the social features of Last.fm are to you.