Anyone out there using SoundCloud?

http://soundcloud.com/

I've looked over the site but can't find where they
explain the necessary widget code.

yes I use SoundCloud.

When logged in, in your dashboard, click on "You" and select "Tracks" - this will list your uploaded material. Then you'll see a player with your audio in it. There's a "share" button at the top of the player, click this, and in the drop down copy the embed code from there.