Soundcloud may be the greatest online file-sharing site since YouTube. In enables artists and hobbyists alike to upload and share music files of any format (until you've run out of your free time - minutes, not megabytes - of which you can buy more by making a premium account) and organize them into sets (playlists). I've been using it to upload and share my latest mixes in order to give clients and friends a sampling of what I'm doing in the studio. If you're not on it yet, check it out and send whatever juicy files you find our way.