I found Lisa Hannigan a couple of years ago whilst I was listening to Damien Rice. Her voice is beautifully melodic, and "I Don't Know" could generally make any one person happy. Good beat, good song to chill out to.
If you want to check out more of her music, visit her website: http://www.lisahannigan.ie/
You can also get a free MP3 of her song "A Sail" by signing up for her mailing list on the homepage.
