Some of my favorites

How to Ask Children to Be In Your Wedding

Cut - Plumb cover by Amy Treadwell

Harmony to Set Fire to the Rain - Adele

Imogen Heap - Half Life - cover with harmony

Fireflies Owl City Harmony

Without You (David Guetta ft. Usher A Cappella Remix)

Sarah McLachlan Love Come - Harmony

Vanilla Twilight - Owl City - Duet with Adam Young

Demi Lovato Don't Forget Cover (with Harmony)

My Makeshift Duet with Alex Goot - Everytime We Touch, Cascada

Bulletproof La Roux Acapella Cover - with harmony

Viva La Vida Coldplay (Harmony!)

Harmony to Josh Groban You Raise Me Up