Sunday
Sunday, Bloody Sunday, U2
Sunday Morning Coming Down, Johnny Cash
Monday
I Don’t Like Mondays, The Boomtown Rats
Monday, Monday, Mamas and the Papas
Manic Monday, The Bangles
Tuesday
Ruby Tuesday, The Rolling Stones
Wednesday
???
Thursday
???
Friday
Friday, I’m in Love, The Cure
Saturday
Saturday Night, Bay City Rollers
Saturday, In the Park, Chicago
Saturday Night’s All Right (For Fighting), Elton John
Sunday
Sunday, Bloody Sunday, U2
Sunday Morning Coming Down, Johnny Cash
Monday
I Don’t Like Mondays, The Boomtown Rats
Monday, Monday, Mamas and the Papas
Manic Monday, The Bangles
New Moon on Monday, Duran Duran
Tuesday
Ruby Tuesday, The Rolling Stones
Tuesday Afternoon, Moody Blues
Wednesday
???
Thursday
???
Friday
Friday, I’m in Love, The Cure
Saturday
Saturday Night, Bay City Rollers
Saturday, In the Park, Chicago
Saturday Night’s All Right (For Fighting), Elton John
Another Saturday Night, Cat Stevens
Monkees–Pleasant Valley Sunday
Tell Me on a Sunday–from the ALW musical “Song & Dance”
Sunday
Everyday is like Sunday - the Smiths
Sunday Sun - Beck
Sunday Night Buttermilk Waltz - the Band
Sunday’s Best - Elvis Costello
Sunday - Lucinda Williams
Monday
Blue Monday - Fats Domino
Come Monday - Jimmy Buffett
On a Monday - Doc Watson
Tuesday
Tuesday Morning - The Pogues (an inferior version of the Pogues sans Shane McGowan)
Sun Comes Up, It’s Tuesday Morning - Cowboy Junkies
Wednesday
Wednesday Morning, 3 a.m. - Simon and Garfunkel
Thursday
…?
Friday
Good Friday - Cowboy Junkies
Friday Night, Saturday Morning - the Specials (works for Saturday, too!)
Saturday
Friday Night, Saturday Morning
One More Saturday Night - Grateful Dead
Saturday Night Holocaust - Dead Kennedys
Another Saturday Night - Jimmy Buffett
(Looking for) The Heart of Saturday Night - Tom Waits
It’s killing me that I can’t come up with a Thursday song.
what hasn’t been mentioned already:
Sunday:
Sunday’s Slave - Nick Cave
Sundays - Lucinda Williams
Sunday Morning Coming Down - Handsome Family
Sunday Girl - Blondie
Sunday You Need Love Monday Be Alone - Trio
Sunday Night is Fair - French Kicks
Wednesday:
Wednesday Week: Elvis Costello
Thursday:
Thursday - Morphine
There are more I have but I cannot type them all out right now…
Thursday’s Child : David Bowie
Happy Days (TV show theme song)
Happy Days Are Here Again
Those Were the Days (not The Tavern; the theme song from All In The Family)
Days of Wine and Roses
Lazy Hazy Crazy Days of Summer
“Sunday Will Never Be the Same” - Spanky and Our Gang
Oh, and Eight Days A Week.
If you’re going to be literal:
“Days Gone Down” - Gerry Rafferty
Stormy Monday - made famous by T-Bone Walker, covered by just about every blues player ever
Monday by The Jam
Groovy Tuesday by The Smithereens
Wednesday Week is also a song by The Undertones
Thursday by Morphine
Friday On My Mind by The Easybeats
S.A.T.U.R.D.A.Y. Night by The Bay City Rollers
and Another Sunday by Yell County 
Daniel Boone - Beautiful Sunday
Scrubbaloe Caine - Feelin’ Good On Sunday
BJ Thomas - Sunday Sunrise
David Gates - Sunday Rider
The Shirelles - I Met Him On A Sunday
Smiley Lewis, Fats Domino, Dave Edmunds, et. al. - Blue Monday
Sonny & Cher - Monday
The Original Caste - Mr. Monday
The Carpenters - Rainy Days And Mondays
The Stampeders - Monday Morning Choo-Choo
Stevie Wonder - Tuesday Heartbreak
Jim Croce - Thursday
Bell & James - Livin’ It Up (Friday Night)
The Turtles - Somewhere Friday Nite
The Sandpipers - Come Saturday Morning
Bobby Russell - Saturday Morning Confusion
Bond - Dancin’ On A Saturday Night
Lynyrd Skynyrd - Saturday Night Special
Jimmy Buffett - Livingston Saturday Night
Rickie Lee Jones - On Saturday Afternoons In 1963
Survivor - Take You On A Saturday
Oh, you can kiss me on a Monday a Monday a Monday
is very very good
Or you can kiss me on a Tuesday a Tuesday a Tuesday
in fact I wish you would
Or you can kiss me on a Wednesday a Thursday a
Friday and Saturday is best
But never ever on a Sunday a Sunday a Sunday
cause that’s my day of rest.
(“Never on Sunday”)
I remembered another one, to my chagrin: Tuesday’s Gone, by Lynyrd Skynyrd.
“Monday Morning” by Pulp.
If you’re going to be extremely literal:
Days - The Kinks
Wednesday’s Child – Emiliana Torrini
Like a Sunday in Salem – Gene Cotton
Saturday Clothes – Gordon Lightfoot
Monday Morning - Fleetwood Mac