There are many popular options out there. Jack Johnson and Michael Bublé are two more famous singers, known for some great acoustic and jazzy tracks. They are certainly worth taking a listen to. However there are a few others out there that are lesser known.
Boyce Avenue is great! They are a fairly new American acoustic rock band incidentally, named after a combination of two streets the brothers lived on as children. Assembled in Sarasota, FL by three brothers Alejandro, Daniel and Fabian Manzano, this acoustic group does a great job giving modern pop music and a new acoustic life.
BRUCE LASH - is another good unknown artist option to look at. Another good cover tune track that I find interesting was featured in the 2008 box office hit Marley & Me. "Lithium" is performed by Bruce Lash and written by Kurt Cobain founder of Nirvana.