Last.fm is one of the top sites for streaming music. It has some great features, including music and video streaming, custom playlist creation, uploading your photos and social networking. 

Using a music recommender system called "Audioscrobbler", Last.fm builds a detailed profile of each user's musical taste by recording details of the songs the user listens to, either from Internet radio stations, or the user's computer or many portable music devices. This information is transferred to Last.fm's database ("scrobbled") either via the music player itself (Spotify, Amarok) or via a plugin installed into the user's music player. The profile data is then displayed on the user's profile page. The site offers numerous social networking features and can recommend and play artists similar to the user's favourites.

Users can create custom radio stations and playlists from any of the audio tracks in Last.fm's music library, and are able to listen to some individual tracks on demand.

Last.fm claims over 40 million active users based in more than 200 countries.

Yahoo has now closed its Music Unlimited service and migrated its customers to Rhapsody; however Yahoo Music is one of the most popular music sites on the Internet.

Yahoo Music provides a number of services which include, streaming music and video, information on artists, and current media news.  You can add videos and music to your own playlist. Well worth a look.

Maestro.fm claims to” take your music to a whole new level”.

Using advances in cloud computing, Maestro makes it easy to listen to your music anywhere. You can create playlists, add songs, and share your library: You also have the ability to store your own digital music library via remote storage.

Using the free Maestro Connector software for PC or Mac, you can build up an online library of songs that can be accessed anywhere in the world via an Internet browser. The use of playlists account for a large part of the Maestro.fm service and you can create, manage, and share them with friends.

imeem is a social media website which brings together people who have similar interests and enables them to interact by sharing media types such as, photos, blogs, messages, and files.

As with most services of this nature, you need to register as a user to access all of its features. Once logged in you will be able to play many more full length tracks and have the facilities to comment, rate, post blogs, etc.