A questionnaire about life changing music - go help these people do their research!
http://www.peopleintomusic.com/

John Lennon's "Imagine" is one song that really is inspiring I would say.

Another one that inspires me iis "Turn! Turn! Turn! (to Everything There is a Season)" sung by The Byrds and inspired by verses in Ecclesiastes.

Funny, one says imagine no heaven, and the other mentions heaven. Go figure.

A classical piece that is inspiring to me is "Also Sprach Zarathrustra" by Strauss. Nothing is more jaw droppingly wow, though Bach's Toccata and Fugue in D Minor is up there too.