Songza provides free streaming music with a snazzy interface. Just type any song or band and add it to your playlist or play it on the spot.

Songza is the single best place to search for and listen to music on the Web. Find a song and listen immediately, in one place.

Unlike KaZaa or Bit Torrent, Songza users can only listen to songs, not download them. And unlike Last.fm or Rhapsody, Songza permits users to choose exactly the song or artist they want to hear, and does not require them to subscribe or pay for its services.

Check out Songza!

Another more commonly known project is Pandora. They will create playlists based on a song or artist you input. A great way to discover new and more obscure music that has the same sound as your favorite artists.

The only downside, unlike Songza, is that you will not be able to play the song you want on demand.

A few others from our readers:
GrooveShark – millions of songs from around the world
Deezer – community music sharing, discovering
SeeqPod – Find. Discover. Watch. Listen. Share.
Ruckus – Free music, with a community for college students. Endorsed by many campuses.
MusicVistas – Similar functionality as Songza, simple interface.

Unlike many other services, these are completely legal, they pay the royalties so you don’t have to. Some even allow you to discover new and fresh music. Enjoy!