There are numerous web services that are designed to help you expand your musical collection in a smart way. They can read your music taste and can then suggest songs, artists and genres similar to the ones that you already love listening to.

Following are some of the best services that can recommend you new music based on what you like already. And since every service uses a different algorithm, they are all worth exploring as you’ll then have a much larger collection of songs and music artists to choose from.

Last.fm Music

Last.fm - One of the first services to recommend music based what you listen to, Last.fm uses their extensive database of user preferences to recommend new songs and artists to you. If you like listening to Artist X and ten other Last.fm users who listen to X have listed Artist Y as their favorite, chances are that you’ll also like Y.

You can download Last.fm’s program on your computer (or iPod Touch) and it will track the songs that you play the most using any of popular media players. It will then suggest you similar music that you can listen to through Last.fm streaming stations - it’s free in the US and UK and €3 per month elsewhere.

Other than desktop offerings, you can also type the name of your favorite band or song on Last.fm’s website to discover similar artists who you may like as well.

Pandora Internet Radio

Pandora Backstage - Pandora is one of the best known sites for Internet Radio and though it is only available in the United States, anyone in the world can use Pandora to discover similar songs, artists and music albums with a click.

Unlike Last.fm which primarily uses user preferences to find similar songs, Pandora uses the sophisticated Music Genome project where trained music analysts analyze hundreds of characteristics of a song to find other similar and compatible songs.

If you are in the US, you can search for song, genre or artist and Pandora will create a custom radio station for you based on favorite songs the user selects that you may listen online or from many mobile devices through specialized apps.

Related: Listen to Pandora Outside US

You can listen to music on Pandora for free for up to 40 hours per month, and unlimited playback is available for $0.99/month.

Grooveshark Radio

Grooveshark offers a beautiful web-based application where you can not only listen to music but also find related songs instantly without even creating an account.

It works like this. You search for your favorites songs and add them to the playlist. Then, click the Radio button and it will automatically add related songs to your playlist based on songs that you already added. If you don’t like a particular suggestion, you can remove that song from the playlist and Grooveshark will try to find another song you might like.

You can search for more songs and add them to your own playlist even while the music is playing, and Grooveshark will dynamically adjust its recommendations based on all of your choices. Grooveshark is free but you can go for ad-free interface by paying $3/month.

Smart DJ without* Zune

PS:You do not need a Zune MP3 player for this to work.

You can search for an artist on the Zune Music website and then click the “Related” tab to discover similar music albums, artists and genres related to the artist. There’s a “influenced” section that shows you other artists who were influenced by the music you are currently listening to.

The Zune desktop software includes a Smart DJ feature that can automatically suggest related songs and albums from Zune’s music catalog based on music albums that already exist in your collection.

You can listen to a 30-second preview of any song, including ones that are automatically added to Smart DJ playlists. If you want more, go for the $14.95/month Zune pass that offers unlimited music streaming to your computer, your Zune MP3 player and/or your web browser. The Zune pass also offers you 10 songs per month that you can store permanently.

Apple iTunes

The Genius Sidebar feature of iTunes can help you discover new music based on what you like already. Select a song in your iTunes library, and the Genius sidebar will show you recommendations live from the iTunes Store. You can preview a 30 second segment of the song and purchase it from the iTunes store directly from the Genius sidebar.

Live Plasma for Music

One of the more innovative ways for exploring music, liveplasma.com generates a bubble graph of other artists who are similar to your favorite band. Simply enter the name of a song or artist you like, and liveplasma will automatically find related artists.

The size of a bubble varies with popularity and the closer a bubble is to your favorite band /artist, that greater the chances are that you’ll like it.

Glue

Glue is a relatively new recommendation engine that is designed to help you find new books, movies, and music based on ones you already like. Enter the name of an artist (or a music album) and Glue will show you similar albums from the same artist.

Tip: Use YouTube to Find Similar Songs

You can not only find a copy of almost every song and music video on YouTube but the other great thing about this video sharing site is that it works great a music discovery engine as well.

Just search for any song on YouTube and then expand the “Related Videos” section in the sidebar to find other music that you may also enjoy listening to. Not all “related videos” may be relevant and some of them may not be music videos at all but you’ll still discover lot of good stuff worth listening to through this technique.