The Piano Guys are an American musical group who gained popularity through YouTube, where they posted piano and cello renditions of popular songs and classical music.

They are also adding piano music books.  This one from amazon.com says:

With their clever and inspiring takes on popular music and creative videos, The Piano Guys serve up an eclectic mix of classical, film score, rock and pop favorites that resonates with a wide variety of audiences.

Play 12 of their most popular songs in these arrangements for easy piano with optional cello: All of Me * Arwen’s Vigil * Begin Again * Home * Kung Fu Piano: Cello Ascends * Moonlight * Over the Rainbow * Paradise * Rolling in the Deep * A Thousand Years * Titanium * Without You.

Includes separate pull-out cello part.

I am not sure about their idea of  “easy piano” but I have ordered a copy for the studio.

Wolf Trap tickets are available here: http://www.wolftrap.org/tickets/calendar/performance/15filene/0806show15.aspx