if your friend has LW (others work too), you can email a magnet link. The friend clicks the magnet link in the email, and if all goes well, his LW will fire up and get the link from your computer.

To make a magnet link, go to the LW Library, select the song, then control-click to bring up the magnet info. Copy the link to your email and see if your friend gets the song.

trap_jaw knows magnets--see here for better info http://www.magnetdb.com/