Susan Boyle's audition on Britain's Got Talent. This is the most inspirational thing I have ever seen on the Internet. And I suspect that many of the 104 million other people who have watched that video feel the same way.
This is a close second. It's The Hallullejah Chorus as it's never been done before or since.
And this is a close third. You really have to listen to this: Charlotte and Jonathan, also auditioning for Britain's got Talent:
Beethoven's Fifth Symphony, Arturo Toscanini conducting
Hit the Ground Running, Gordon Goodwin's Big Phat Band. I normally don't like jazz solos but listen to Eric Marienthal's sax solo on this.
The Overture to the iconic 1994 Barbra Streisand concert. I believe that overtures are underrated music.
Debussy's Clair de Lune, David Oistraikh, violin, Frida Bauer, piano.
High Iron Mama, Tom Brigham and his band. This is just an audio sample but I really like it and it's very different from everything else in this post, so I decided to include it.
He's the Greatest. John P. Kee and the New Life Choir. I'm an atheist but I find music like this to be an antidepressant...and it has no side-effects.
The Way You Look Tonight, Beegie Adair trio. It's easy to dismiss easy-listening music. I don't. This is a good example of why.
Chopin's Polonaise (Heroic): Evgeny Kissin, piano.
A Few Good Men: Gordon Goodwin Big Phat Band. This contains another amazing solo: Karl Verheyen on guitar. It starts at 1:47.
Beethoven's Piano Trio Op.70 (The Ghost): Emanuel Ax, piano;, Isaac Stern, violin;, Yo-Yo Ma, cello.
Overture to the Fantasticks
The Aria from Bach's Goldberg Variations: Glenn Gould, piano. I think this is the music I'd want playing on my deathbed.
By the way, I highly recommend Klipsch ProMedia 2.1 computer speakers: about $75 used on Amazon.