I know you guys probably get tired of me plugging Green Linnet...but they published (whatever the right word is in the music industry!) several of Silly Wizard's albums, as well as all of Lunasa's, and they have whole albums you can listen to on-line! (Provided you have a decent connection speed, that is!)
Try here.
To borrow one of 2JMs favorite lines "Fetch My Medicine"! I'm listening to "Noels Celtiques"; a CD of music from Brittany. It starts with a song I've heard before, but don't know the name. It is just a lovely tune with awesome harmonies!