Killing Me Softly with His Song inspired by a poem written about Don McLean’s Empty Chairs.
What are some others?
Them good old boys were drinking whiskey and rye
Singing “this’ll be the day that I die”
And the band played Waltzing Matilda
There’s always the classic **I’ve Been Workin’ on the Railroad ** lyrics:
Someone’s in the kitchen with Dinah
Stummin’ on the old banjo
And singin’
Fee Fi Fiddlie Eye Oh…
Sweet Home Alabama was about Southern Man.
Thanks for the suggestions, but I was looking more for songs that are written about other songs,not that mention other songs.
I think that Sweet Home Alabama qualifies. The whole song was written as a sort of protest against the portrayal of the south in the song Southern Man, wasn’t it? It mentions it, yes, but it’s also basically a refutation of the stuff said in the other song, so it is in a way “about” the other song.
Tenacious D’s Tribute. 
I agree.Didn’t see that before posting.
Look What They’ve Done to My Song, Ma, by Melanie, although I don’t know if it has anything to do with an actual song or uses it as a metaphor.
Ashes to Ashes by David Bowie, sort of. (“Do you remember a guy that’s been in such an early song [Space Oddity].”)
Song of Solomon by Kate Bush (“The Song of Solomon, the song of everyone who walks the path of the solitary heart”).
The Mamas and The Papas “Creeque Alley”
- and California Dreamin’ is becoming a reality*
The Beatles - ‘Glass Onion’
Some lines
I told you about strawberry fields
You know the place where nothing is real
Well here’s another place you can go
Where everything flows.
I told you about the walrus and me-man
You know that we’re as close as can be-man
Well here’s another clue for you all
The walrus was Paul.
Lady Madonna trying to make ends meet-yeah
Looking through a glass onion.
I told you about the fool on the hill
I tell you man he living there still
There’s also a reference to ‘Fixing a Hole’, though I have a feeling that song was released after Glass Onion, though I’m not sure.
Pretty cool because it’s a Beatles song that references other, past Beatles songs.
Speaking of which, Peter Schilling’s “Major Tom Coming Home” is a retelling/continuation of the story from “Space Oddity” isn’t it?
David Lindley’s song Pay Bo Diddley is a rewrite of Hey, Bo Diddley. The song is about Bo getting screwed over royalties, and song credits go to Bo.
Bruce Springsteen’s Thunder Road was inspired by Roy Orbison (according to liner notes) and contains the line “Roy Orbison sang for the lonely.”
“Fixing A Hole,” Sgt Peppers Lonely Hearts Club Band, 1967
“Glass Onion,” The Beatles, 1968
“I Walk the Line (Revisited)” by Rodney Crowell, featuring then-father-in-law Johnny Cash
“This Song” by George Harrison, his reaction to losing a plagiarism suit for “My Sweet Lord.”
“Daddy Sang Bass” by the Oak Ridge Boys, about singing “May the Circle Be Unbroken” in a family band
Michelle Shocked’s “Frankie and Johnny” bears just little enough resemblance to the original to maybe qualify
Another George Harrison possibility: His sad version of “Bye Bye Love” is generally considered a response to Eric Clapton stealing is wife Patti. I wonder if it wasn’t more specifically a reply to Clapton’s “Wonderful Tonight”?
Weird Al Yankovic’s “(This Song Is Just) Six Words Long” is about George Harrison’s “(I Got My Mind) Set On You”.
I count seven words… Guess it didn’t scan. 
Are any of his other parodies directly about the parodied song?
*** Ponder
Matthew Fisher’s “Going for a Song” is about Fisher getting sick and tired of playing the same song over and over again. Though he doesn’t mention the name, it’s clear what song he means: he throws in a phrase of “A Whiter Shade of Pale,” on which he played (and perhaps composed) the organ riff that identifies the song.
One of her finest, no doubt.
“More than a feeling, when I hear that old song babe.” ~Boston.
Not about a specific song but the power of a song.
R.I.P. Brad Delp.