Recently Zac Bissonette shared the sad news that Ruckus, a provider of "free" music to college students, closed down. While he is turning to YouTube to feed his musical cravings, there are many other options out there to satisfy even the most demanding musical tastes. Thanks to the wonders of technology -- and music licensing -- you can listen to millions of free tracks online and even take several of these free options with you on the go.

All of these streaming music services are free for all to use with minimal advertising. In some cases, you can subscribe for a nominal fee to remove ads and unlock extra features, but the free versions will often scratch your musical itch just right. Either way, it's still cheaper than being on the receiving end of an RIAA lawsuit!

You can use all of the services from your computer and the compatibility chart below to see which ones you can take with you on popular mobile phones.

Service iPhone Blackberry Android G1 Windows Mobile Pandora X X Last.fm X X X Slacker X X Shoutcast X X* X* Blip.fm X* AOL Radio X X*

* needs a third party program which may cost money.

Keep reading to find out more about each free music offering.

Pandora: By far Pandora is one of the best known brands for free online music. Pandora makes use of the Music Genome project to search out artists and songs that "fit' whatever music you feed it. Using Pandora is straightforward and literally falls into the "So easy my mother in law can use it" category; and in fact she does. With a broad music catalog, extremely limited commercials and an eerie ability to know what you want to hear at any given moment; it's clear that Pandora is one of the top contenders for online streaming.

Last.Fm: Last.Fm is similar to Pandora in that it also will serve up music based on your preferences and can learn from your listening habits. But that's where the similarities stop. Last.Fm also brings a social component to streaming music. Not only can you share what you're listening to at any given moment with your friends, but you can also listen to stations of your "neighbors" who share similar tastes. Last.Fm is an amazing source for discovering new music, and if you end up hearing a song you can't stand you can always ban it from your playlist.

Slacker: This streaming music service is perfect for anyone too lazy to craft a playlist, whether you are looking for the perfect mix for work, a Saturday night party or chillin' on Sunday afternoon Slacker has you covered. With over 100 stations spanning 16 genres the Slacker service has an expertly-crafted playlist for everyone. If the pre-built stations aren't up your alley, you can also create your own based on a particular artist or song. Additionally, Slacker is the only service which works without an Internet connection, though you'll need a Slacker MP3 player to pull that off.

Shoutcast: Shoutcast doesn't stream music based off of a recommendation system like the first three, but it does offer an impressive selection of stations, including diverse categories such as Croation and Chinese to compliment Beatles and Alternative stations. If you aren't satisfied with the numerous available stations, you can even download software to become your own Internet DJ.

Blip.Fm: With Blip.Fm you can become your own DJ without downloading any software. By signing up to become a DJ with Blip.Fm you'll have access to millions of streaming songs and integration with all the big social networking sites. If you're not up to picking every song you want to hear you can also friend DJs with similar tastes to keep a constant stream of music coming.

AOL Internet Radio: Powered by CBS Radio, the offerings of AOL radio are far reaching and let users tune into their local stations no matter where they are. AOL radio also provides access to talk and sports radio from your favorite announcers. Access to morning and afternoon talk shows is only the beginning with many more music stations in any genre you can imagine rounding out the auditory offering.

Bonus - Spotify: While most of the previous stations are only available in the U.S. Spotify is currently only available to listeners in the UK and offers access to unprecedented numbers of tracks for free. With plans for a mobile client in the near future, it's no wonder those of us in the states can't wait for Spotify to hit our shores!

The downside to these services of course is that you need an Internet connection and often times cannot choose a specific song to listen to. If you can't get by with songs that are similar to "Paint it Black' when you really need to hear the Stones, then I highly recommend purchasing a music subscription service like Rhapsody which offers cheap access to a huge library of music.

Though unless you are a huge consumer of music or crave access to a large back catalog of tunes you may find it cheaper to purchase the individual tracks from Amazon.com's DRM free mp3 store or snag the whole CD cheap at your local pawn shop.

Between these streaming music outlets you're sure to find the right set of tunes without even opening your wallet. Personally I enjoy keeping them all handy so that I'm never without the music I'm looking for. With the money you save listening to these free tunes maybe you'll have enough saved up for the summer concert season!