No one has mentioned one almost as famous as "Stairway..."

Free Bird - Allen Collins w/Lynyrd Skynyrd

Aqualung - Martin Barre w/Jethro Tull

Reelin' in the Years - Eliott Randall w/Steely Dan

Just about anything by Larry Carlton with Steely Dan...so many (Kid Charlemagne and Josie come to mind).

While My Guitar Gently Weeps - most people think George Harrison did this, but it was really Eric Clapton.

Blue Sky - Duane Alman/Dicky Betts

Beat It - Eddie Van Halen

'Cause We've Ended as Lovers - Jeff Beck


...WAY back there: Chuck Berry: Johnny B. Goode (the original)