Thanks to the Internet Archive's new FreeCache project, you can conserve your bandwidth when posting links to your MP3 or other media files.

Just stick the URL: http://freecache.org/

...in front of your own URL. Like this:

http://freecache.org/http://yourserver.com/yourfile.mp3 (don't click this -- it's just an example)

The system will locate another server that has already downloaded and cached the same content, saving your server a headache and speeding up the download for your listener.