Play It Again Sam: 12 Music Streaming Services Sound Off
Slacker

Much like Pandora, Slacker is primarily a radio streaming service with stations programmed by expert DJs. Slacker allows users to create and share customized stations, and has over 10 million songs, organized into over 150 programmed stations with 10,000 artist stations including comedy, news and ESPN.
Slacker’s dashboard is fairly straightforward and centers around a wheel that features the album art of the song playing. A drop-down menu gives users a link to copy the station, fine tune, and add to favorites. A search bar is neatly tucked between the album art and the audio controls—including the option to go back a song. Left hand navigation buttons allow you to browse stations and genres, show current station info and create a station. Users can store playlists, entire albums and stations and can sign in with Facebook for quick access and additional social networking features. Its drawbacks? A limited number of song skips, and no ability to upload your own music collection to the service.

Pricing: Free (ad supported). Slacker Radio Plus $3.99/month removes the ads, gives you an unlimited number of song skips, news and ESPN stations and complete song lyrics. Slacker Premium Radio $9.99/month gives you all of the above plus the ability to play songs or albums on demand, create single-artist stations, cache albums and create playlists.
Availability: Web browser, BlackBerry, iPhone, iPad, iPod Touch, Palm webOS, Windows Mobile, Windows Phone7, Nokia, Sony, Sonos, Logitech, Acoustic Research, Slacker Portable Radio.
Google Music

Created by the big “G” to enable users to “discover, buy and share music, wherever you want, whenever you want” – and to give Android fans the functionalities of iTunes, much ado has been made about the recently released service. Google Music was designed to work seamlessly with Android Market to offer music recommendations, stream music, store it, and create an instant mix.
With hundreds of free songs, and millions more to buy on Android Market, Google Music is off to a good start. Music is automatically stored in your Google Music library and instantly ready to play or download. Google Music allows you to store up to 20,000 songs for free – but (and it’s a big but) everything is stored in the cloud. While that does save room on Android devices, and allows you to listen to your library without worrying about syncing or wires, it also comes with the limitations and security problems inherent in cloud storage.
Google Music definitely is born to work within the Google/Android environments: you can easily share and listen to your music with your Google+ friends, and the dashboard and locations of commands is akin to Gmail. You can upload your songs in order to organize and store all of your music in one place, create a playlist using Instant Mix, import from iTunes, and save favorite tracks to your mobile device for offline listening.

Pricing: Storage: 20,000 songs for free. Purchase: Songs individually priced.
Availability: Web browser, Android devices, or devices that use Adobe flash.
Amazon Cloud Player/Amazon MP3

Amazon’s online music store launched in 2007, and was the first store to sell music from the four major labels – without DRM. It has an impressive catalogue of over 18 million songs (although some of them do have watermarks) although it only supports AAC and MP3, it’s been a standard in online music since its inception with the Cloud Player music streaming service launched last year, it's only improving that reputation.
Amazon’s cloud service is designed more for those who want to purchase and store their tunes: it saves purchased music into a folder, and purchased tracks can be added to Windows Media Player or iTunes libraries automatically but does not allow users to sample entire songs on the site – just a preview. Although you can upload your own songs into your music folder, it must be done using Amazon’s MP3 Uploader. However, it does enable users to stream their collections over a variety of devices – including the Kindle Fire.

Pricing: 5GB free. $20/year gets you unlimited space for music and 20GB of cloud storage. There are also 50GB ($50 per year), 100GB ($100 per year), 200GB ($200 per year), 500GB ($500 per year), and 1000GB ($1,000 per year) options available.
Availability: Windows, Max OS X, Linux, Kindle Fire, Android. Preloaded on TMobile G1, Palm webOS, and Droids.