Twitter is a popular social network where people share bits of their life or pass along information in 140 characters or less. Twitter's simplicity has helped rocket the service from small start-up into the mainstream. Twitter itself does not allow a user to upload music, but just as with photo and link sharing, other services have stepped up to allow Twitter users to easily upload and/or share music with friends and followers. There are numerous resources to help you pass along music to friends via Twitter.
Share music with Blip.fm. Blip.fm allows users to search for any artist or track. If it cannot find the particular track you are looking for, you can upload it. You can give Blip.fm your Twitter credentials to automatically "tweet" (post) a short URL to the track. Blip.fm has the ability to add followers on the service itself, outside of Twitter, creating a stream of only shared music.
Search for the song on TinySong.com. TinySong is a service by the same people who provide the GrooveShark streaming music service. TinySong provides an extremely simple interface with a singular search box (akin to the Google homepage) and will provide results from the millions of tracks within GrooveShark. A short URL is provided for users to copy and paste into their Twitter posting to share.
Share songs via iTunes. iTunes' latest update provides a "Share" button next to every track. Clicking the drop-down menu next to the "Buy" option, you can easily share a song via Twitter or Facebook. Sharing the song provides a short URL, which will bring users to that song within iTunes.