Hi David, It's not the same as embedding a full-length pre-recorded sample of your work, but ooVoo (free application) lets you send one-minute video messages via email. Maybe you could use it to send a 'taster' example message and then embed a link to your site/a holding page with the work itself? Just an idea.
Other than that I have tried this before and not had much luck I'm afraid so would be interested if anyone else has too.
