Well, I'll throw out my list of the "stuff everyone does," at least what it seems to be around here. Just culling from old playlists.
Sublime - What I Got
Black Crowes - Hard to Handle
Mustang Sally, duh.
Skynyrd - Gimme Three Steps, Sweet Home Alabama, Simple Man, and yes, Freebird
Bryan Adams - Summer of 69
Romantics - What I Like About You (easy to medley with ROCK in the USA and other songs if you like a power drill to the skull)
Ramones - I Wanna Be Sedated (especially if you had a gig this past NYE)
Joan Jett - I Love Rock and Roll, I Hate Myself for Loving You
Pat Benatar - Heartbreaker, Hit Me With Your Best Shot
Jenny Jenny (867 5309), by whoever that was.
My Own Worst Enemy
No Doubt - Just a Girl
Superstition (per Stevie Ray or Wonder)
Doobie Bros - Long Train Running
GA Satellites - Keep Your Hands to Yourself
Wild Cherry - Play That Funky Music White Boy
Neil Young - Rockin in the Free World
MaCoys - Hang on Sloopy
Tom Petty - American Girl, Mary Jane's Last Dance, You Wreck Me (can medley with U2, Desire, and others)
Marshall Tucker Band - Can't You See
Doors - Roadhouse Blues
CCR - Proud Mary, Fortunate Son
Stevie Ray - Pride and Joy
I Want You to Want Me
3 doors down - Kryptonite
Jimmy Eat World - The Middle
Hey Jealousy
Weezer - Hash Pipe
AC/DC - You Shook Me All Night Long, Dirty Deeds, TNT
Aerosmith - Walk This Way
Cream - Sunshine of Your Love
Stones - Satisfaction, Jumping Jack Flash, Honky Tonk Women
Johnny Cash - Folsom Prison Blues
Jet - Are You Gonna Be My Girl
Wagon Wheel
Melissa Etheridge - I'm the Only One (if there's a female singer, they're bound to want to do this)
whatsername - Bitch (ditto)
Alanis - You Oughta Know (double ditto)
Santana - Black Magic Woman (if there's a guitarist in a certain mood)
Eddie Money - Two Tickets to Paradise
ZZ Top - La Grange, Tush
Brown Eyed Girl
Steppenwolf - Born to Be Wild
Probably a bunch I didn't think of. This is not my recommendation for a set list I would use if I were starting a cover band - trying to hit my market's answer to the OP's question, what's the stuff that pretty much every cover band plays, the bog-standard stuff that most musicians who have been around a while have played sometime in their memory. There's some artists not represented - for example, it's pretty likely that a band would have a Beatles tune in the repertoire, probably everyone knows some Beatles tune or other, but there's no one or two Beatles tunes that EVERYONE plays. Same for Zeppelin, same for some bands that are on the list where the one I listed is most likely the one that everyone around knows but you'll see some bands play a different song by the artist.
The list doesn't include much recent music because the bands generally don't know it unless it's part of their identity. Some will know Take Me Out or Exes and Ohs or Mr. Brightside or Locked Out of Heaven, but I wouldn't walk into an open mic and assume that there are musicians present who know them.