Wasn’t Me & Bobbie McGee by Janis Joplin?
Avenging Annie by Andy Pratt, though Roger Daltrey’s cover is a lot better.
Crazy On You by Heart.
And can’t forget, Bad Girl by Wendy O. Williams and The Plasmatics. 
Written by Kristofferson. Joplin’s memorable cover has left a lot of people thinking she also wrote it.
Joni Mitchell’s Cactus Tree comes to mind, although the point of the song is that the ‘free-spirited’ woman is really a cold-hearted bitch with fear of intimacy issues.
Martha - Jefferson Airplane
No Salt On Her Tail - the Mamas & the Papas
Rock & Roll Woman - Buffalo Springfield
And just to show that not only classic rock groups exploit this cliche, there’s -
There She Goes - the La’s
Black-Eyed Susan - Paul Westerberg
Valerie Loves Me - I forget who did this.
Dylan’s “She Belongs To Me” might qualify, although the woman described there might be less “freespirited” and more “downright dangerous”.
“The Girl’s Distracted” - Saturday Looks Good to Me
Flying Sorcery by Al Stewart
My apologies if some of these have already been mentioned, but cut ‘n’ paste is so easy. Here’s the playlist for a mix CD I made once for a Women’s Mysteries class - the title of the collection is, unimaginatively enough, “Maiden Songs”. Some of them are sung from the POV of a strong young woman, some of them *about *strong young women, and some of them just gave us the feeling, the mood, of strong young women.
**Maria **- Jane Siberry
He Moved Through the Fair - The Chieftans (with Sinead O’Connor)
The Sun and the Moon - Heidi Berry
**Vox **- Sarah McLachlan
Aparna and Ninisha (Dobro #5) - David Sylvian
Just Like Honey - The Jesus and Mary Chain
Maid of Orleans - Orchestral Maneouvres in the Dark
One Day - Bjork
I Kicked a Boy - The Sundays
**Girl **- Tori Amos
The Child is Gone - Fiona Apple
Honey Bee - Jane Siberry
Joey - Nick Drake
I’m Under Your Spell - Amber Benson (from the Once More, With Feeling soundtrack)
Fire Woman - The Cult
**Bitch **- Meredith Brooks
I’m With You - Avril Lavigne
So Young (K-Klass Remix) - The Corrs
Rubberband Girl (US Mix) - Kate Bush
Charge of the Star Goddess - Shawna Carol
“I Kissed a Girl” by Jill Sobule
“These Boots are Made for Walking” by Nancy Sinatra
“I Like 'Em Big and Stupid” by Julie Brown
“All the Relatives” by Christine Kane (Yeah, I know, “Who?” But it’s an awesome song.)
“And all the relatives, they say she’s always been crazy with her her radical ways
They say she’s ornery, smells sorta garlicky, they think she might be gay”
The group “Oxo” released a single called “Whirly Girl” (which was easier to sing than “Worldly Girl”), about the lead singer’s wife, who apparently had done some groupie-ing with rock stars in the past.
“Oxo” then became “Company B,” (single “Fascinated”) and his wife was actually one of the vocalists.
She Don’t Use Jelly - Flaming Lips
Punk Rock Girl - The Dead Milkmen
Raspberry Beret - Prince
(She’s) Sexy and 17 - Stray Cats
Simple Twist of Fate - Bob Dylan
Lady Godiva - Peter & Gordon
Pre-Madonna - Kursaal Flyers
Sally Simpson - The Who
It’s My Party And I’ll Cry If I Want To - Lesley Gore
O.K, maybe not the last one…
Immediately thought of “Freeway”, by the Canadian country girl group Farmer’s daughter 
“She’s Not In Love” by Kim Stockwood (again dipping into the Canadian grrl music ).
Thanks, these are great! I’m particularly going to go check out Scarlett67’s intriguing choice. Thought of a few more, too:
By Joni Mitchell: Ladies of the Canyon and Roses Blue
About Joni Mitchell: Cowgirl in the Sand and Guenevere
Neil Young’s Unknown Legend
Al Stewart’s Year of the Cat, Delia’s Gone and Sand in Your Shoes
The Acid Queen by the Who
…and the granddaddy of them all: Suzanne, by Leonard Cohen.
Almost enough for a hippie-chick double album. 
Chevy Van - Sammy Johns
Material Issue, iirc
Magic Trick by M. Ward.
Besides covering Me and Bobby McGee, Gordon Lightfoot also wrote and performed such tunes as
Daylight Katy and Approaching Lavender.