Enter Soundcloud, a service that allows you to send, receive and store original music files in one easy location.

Start by creating a free account. From there, you can easily search the site for music and either set tracks as a favorite, download them or share them with others.

If a friend or artist creates a track that they think you should hear, they can easily forward it to your “dropbox.” You can even create a link button for your Facebook page so friends can always add music.

Soundcloud is incredibly fast and there are no limits to file sizes (all formats accepted). You also have control over who gets to listen to your music (stats are compiled on who has listened and downloaded your tracks).

For bands or artists who want unlimited sharing, better stats and full support, there’s the premium service (they start at around $36 per year).

Your mixtape days are about to start again.

Playing music on your computer is great.  But sometimes you want to play it in other places throughout the house.

Luckily, there’s Airfoil, a downloadable program that allows you to stream audio simultaneously to almost any media device in your house without the use of an extra router.

Simply download and install the software (it costs $25 and both Macs and Windows-based PCs are supported).

Airfoil syncs audio on all of the supported devices on your network, which includes laptops, PCs, iPhones, iPod Touches, and Apple TVs, turning your gadgets into a wireless speaker system.

From there, just let the music play (from the internet or your mp3 collection). The software lets you select various devices throughout your house, and they play the music as well.

You are now free to air guitar throughout your house.

Enter Blip.fm, a new service that allows you to play DJ by creating (and listening to) custom playlists, song by song.

First, choose your DJ name and list a few of your favorite musical acts (a wide range of choices works best).

From there, Blip will compare your taste in music with data from other users. When you find users you like, you add them to your DJ homepage, which uses a Twitter-like streaming format to show updates (or “Blips”) each time a fellow DJ plays a new song.

Click on a song to play it.  As it plays, you’ll also see the music video (if one is available).  If you like the song, you can add it to your profile.

When you get tired of listening to the work of other DJ’s, begin selecting songs to add to your own custom playlist. You can even add messages to each blip, so others know why you’ve chosen it when it shows up on their stream.

(The sharing isn’t just limited to other Blip users, either. You can broadcast your picks on a variety of social networks, including Twitter and Tumblr.)

All the music is available for free, making Blip.fm an incredible source for listening to your old favorites and learning about new ones.

Your listeners are waiting…

But consider the fact that it means you can get podcasts, live music bootlegs and endless hours of other forms of entertainment, all for free.

This is the logic behind Dirpy, a tool that allows you to convert your favorite YouTube videos into high quality mp3s, all in real time.

To start, enter a search term on their homepage and you’ll see a list of video results. Click on the one you want and you’re taken to what they call the “transcoder” page.

Here you’ll be able to name the clip, pick the quality of the audio and even customize the start and end time for the file (in case you only want part of the clip).

You can also edit the ID3 tag information, to make sure the newly created file dovetails neatly with your online music player’s existing collection.

Finally, a way to add that rare version of Susan Boyle singing “I Dreamed A Dream” to your iTunes party mix.

That’s the notion behind Amie Street, a music site that offers a unique progressive pricing structure that lets you save money for selecting music before it gets popular.

When a new song or album is added to the site it’s available for free or very cheap (the site doesn’t specify a maximum starting price).

The price only goes up as demand for a song increases (in terms of total downloads).  The more attuned you are the cheaper your music prices will be.

And even if you’re late to an artist, the highest price a song can reach is 98 cents (one cent below the starting price for songs on an unnamed service started by a guy who favors mock turtlenecks).

The site also rewards users for recommending new music. If you recommend a song that happens to get popular, Amie Street will credit your account as more users download the track (the amount of credit you receive increases as the song gets more popular).

And, in a nod to its open-source philosophy, Amie Street encourages artists to upload their own music.

In other words, you can finally distribute that demo you’ve had in your desk drawer for years.

Try Grooveshark, a simple-to-use music streaming service and search engine that allows you to listen to streaming audio from tens of thousands of artists. For free.

(In other words, almost anything you’d want to hear, though they were just sued by Universal, but let’s not dwell on that).

Using their drop-dead simple interface you search for an artist, song or genre and Grooveshark will provide matches.

You can listen to a track immediately or add it to a custom playlist to enjoy later.  You can also export it to your desktop and play it via their downloadable widget.

To take advantage of the site’s social networking abilities sign up for a free account (a “VIP” account costs $3/month and makes it ad-free). From there, you can browse the playlists of other users and share your songs with friends.

Grooveshark also functions as an Internet radio service (akin to Pandora). Just enable the radio option while playing any song and the app will record your preferences and provide a steady flow of songs based on your tastes.

So go ahead and let the music play.

To recapture some of that programming magic, try 8tracks, a free service that allows you to create and share the digital equivalent of online mix tapes.

To make a mix you simply pick any 8 songs (about 30 minutes of music) using the site’s drag and drop functionality.  8tracks allows you to search their network of previously uploaded tracks by song, artist or genre. You can also upload music from your own library.

When you’re done you can add artwork and short descriptor to your masterpiece.

Publishing a mix tape allows you to share it with the 8 Tracks community and with your friends (or, if you want, just one special friend), via Twitter and Facebook

You can also listen to any of the 65,000 mixes already on the site (we found some great ones and discovered a ton of new music along the way).

As for that old Nakamichi tape deck you still own?  Leave it in the closet to collect dust.

Luckily there’s Livekick, a concert ticket search engine that provides concert recommendations (based on your musical tastes and locale) and then helps you buy tickets at the cheapest available prices.

The site uses your zip code and your listening habits (you either enter your favorite artists manually or the site can glean the info from your iTunes library and other digital music services) to figure out when the bands you like will be in your area.  Livekick will also make concert recommendations based on those preferences.

When you find a show or an artist you want to see you click on it and the site takes you to a page that aggregates tickets with real-time pricing from the top ten online sellers, including Ticketmaster, StubHub and Tickets.com. The page also has venue information and arena maps (so you can see how good your seats will be).

Download their widget and it’ll scan your digital music libraries and recommend shows based on what it finds.

You will, however, have to bring your own lighter to the show.

Luckily for you, there’s Slacker, a customizable internet radio service that lets you enter a song or artist and comes back with a never ending stream of personalized song recommendations.

Slacker offers many of the features found on sites like Pandora and Last.fm, including the ability to skip songs (it’s limited to 5 an hour), mark favorites and access your stations across any platform, all for free.

(True buffs can upgrade to Radio Plus for $4.99/month, which removes all restrictions and ads.)

However, what differentiates Slacker is its customizability. As part of every stream, users can further control what will show up, from picking certain songs to highlighting a specific time period or genre.

You can also use it on the road, whether through their mobile apps for iPhone, Android and Blackberry (the app layout is actually better than their web interface) or via their branded player, which runs for $130 and resembles a slightly pudgy iPod.

So if you’re looking to broaden your musical horizons, or just want to put your collection on ice, Slacker will be there to hold your hand.