Brian Vander Ark. You can listen to a couple of his songs, streaming, here:
http://www.myspace.com/brianvanderark
You might already be familiar with his vocals...he was and is the lead singer of the Verve Pipe.
Also, if it's not just mellow stuff you're interested in, try some Ted Leo and the Pharmacists from the below two links (free, legal mp3s):
http://www.epitonic.com/artists/tedleopharmacists.html
http://www.lookoutrecords.com/sounds/index.php3
Really quite uplifting, a lot of Leo's stuff is.