I’m at the coffee machine in my local ShopRite when the overhead music segues from “Knock Three Times” to “Knock on Wood.” Remembering the Dylan thread, I say “What’s next? Knocking on Heaven’s Door.”
The guy standing next to me says “I Hear You Knocking.”
I want to put together a jukebox musical called “KNOCK-KNOCK.” I need some more songs about knocking.
Mighty Mighty Bosstones - ‘The Impression That I Get’
“I’ve never had to knock on wood / but I know someone who has / which makes me wonder if I could…”
“Let 'Em In” - Paul McCartney & Wings
Someone’s knocking at the door
Somebody’s ringing the bell…
From the 80s:
“Who Can It Be Now?” - Men At Work
Who can it be knocking at my door?
Go 'way, don’t come 'round here no more.
“Somebody’s Knocking” - Terri Gibbs
Somebody’s knocking should I let him in
Lord it’s the devil would you look at him
(Interesting, but a little obvious when you think about it, that many songs have a reference to ‘knocking’ in the opening line!)
Another from the 80s:
“Empty Garden” - Elton John
And I’ve been knocking
But no one answers
The Stones - Can’t you Hear Me Knocking - From Sticky Fingers
The old bawdy folk song “Barnacle Bill the Sailor”:
“Who’s that knocking at my door? Who’s that knocking at my door?
Who’s that knocking at my door?” said the fair young maiden."
The full version is very NSFW.
There’s a Spike Jones tune that’s basically a series of knock knock jokes but I can’t recall the title at the moment.
“I Hear You Knockin’” Smiley Lewis (covered by Dave Edmunds)
“Keep a Knockin’” Little Richard
And with knocking in the lyrics though not the title:
“Open the Door, Richard” The Three Flames
“Ain’t Nobody Home” B.B. King
“Love Shack” - B-52s
I’m not sure which song you mean by “Knock on Wood,” but I want to make sure we include the Dooley Wilson song from Casablanca
How about Beethoven’s Fifth Symphony?
I understand the famous four-note opening (da-da-da-DUMM) was supposed to suggest fate knocking at the door.
“Knock Knock” - 1200 Techniques
They don’t knock…they “bang, bang, bang on the door baby.” 
Unless of course you’re talking about Kate Pearson’s enormous knockers!:D:D
Knock a little louder! 
Mama Said Knock You Out
Also, Peter Gabriel’s Games Without Frontiers, for the line “…it’s a Knockout”
“Knock Knock, Who’s There?” by Mary Hopkin.
Knock knock, who’s there?
Could this be love that’s calling?
The door is always open wide.Knock knock - who’s there?
Now as the night is falling,
Take off your coat and come inside.
Hmm, I thought I had about all of Spike’s stuff, but I don’t remember that one. However, there is a PDQ Bach piece consisting of knock knock jokes as recitative on his Oedipus Tex album.
I’m pretty sure that on one Prairie Home Companion joke show there was a knock knock joke song.
“I’m Fucking Matt Damon” by Sarah Silverman
Found it! “Knock Knock, Who’s There?” 12 jokes and three(?) choruses in just under 3½ minutes, ending in one of Doodles’ announcer bits.
