Not to mention “She’s Goin’ Bald.” 
I Think I’m Going Bald - Rush
Here, There and Everywhere: “running my hands through her hair”
"Well Delilah was a woman, she was fine and fair,
She had good looks, God knows, and coal black hair,
Delilah she gained old Samson’s mind.
When first he saw this woman, you know he couldn’t believe his mind.
Delilah she climbed up on Samson’s knee,
Said tell me where your strength lies if you please.
She spoke so kind and she talked so fair,
Well Samson said, Delilah cut off my hair.
You can shave my head, clean as my hand
And my strength will become as natural as any old man."
just saying… I understand the struggle!
A couple of these haven’t yet been mentioned:
Touch of Gray - The Grateful Dead
Uneasy Rider - Charlie Daniels
Box of Hair - Cub
Straight Lines - Suzanne Vega
Little blond plaits - Chris Rea
The Hair Song by Black Mountain is great
Not entirely a hair song, but its most striking line is about hair - “Sitting” by Cat Stevens.
Every time I hear it, I shake my head and think: So, you feel the power growing in your hair, do you? Hey bub, a little psychiatric consultation might not be out of line.
JoJo the Dog-faced Boy? He’s certainly got hair…/
The legendary German punk band die Ärzte did a concept album about hair called “Le Frisur”. It contained gems like “Vokuhila Superstar” (“Mullet superstar”), “Dauerwelle vs. Minipli” (“Permanent wave vs. minipli”), “Der Afro von Paul Breitner” (“The afro of Paul Breitner”) and “Hair Today, Gone Tomorrow”. It’s really, really funny.
The Nuclears - “Hair Stays, You Go”
Ah yes, how could I have forgotten?!
I don’t want no bald-headed woman.
The Kinks: Permanent Waves
Bob Dylan’s “The Girl from the North Country” has a verse about hair –
Please see for me if her hair hangs long,
If it rolls and flows all down her breast.
Please see for me if her hair hangs long,
That’s the way I remember her best.
Was gonna mention another along these lines earlier, but wasn’t sure if songs about the absence of hair would be welcome!
So let’s add “Bald-Headed Lena” by The Lovin’ Spoonful.
And Shel Talmy, the Kinks/Who producer who wrote “Bald-Headed Woman,” seems to have had some sort of a fixation going, as he also wrote “I’ve Been Driving on Bald Mountain” for The Kinks.
Wig in a Box from Hedwig and the Angry Inch.
Rod Stewart’s “Blondes Have More Fun.”
Arguably not a song about hair, nor even a song:
Bulbous Bouffantby the Vestibules