Hmmm. Just put in our list, plus the question marks, and it said we only had 48 right. I'm guessing syntax was an issue. Before I leave work, here's the collective list as I have it right now...

63 artists:
Guns N Roses
Nine Inch Nails
Smashing Pumpkins
Radiohead
Red Hot Chili Peppers
Matchbox 20
Eagles
Alice in Chains
Led Zepplin
White Zombie
Gorillaz
Scissor Sisters
Rolling Stones
U2
50 Cent
Crowded House
Sex Pistols
Pixies
Monkees
Whitesnake
B-52s
Ratt
Black Flag
Eels
Blind Melon
Blur
Police
Madonna
Black Crowes
Talking Heads
Iron Maiden
Seal
Dead Kennedys
Garbage
Cars
Hole
Cowboy Junkies
Phish
Cranberries
Eminem
Queen
Doors
Postal Service
Great White
Yellowman
Green Day
Beach Boys
Prince
Vines
Lemonheads
Korn
Jewel
Carpenters
Cypress Hill
King Kong
Deep Purple
Kiss
4 Non Blondes
Spoon
Bee Gees
Cake
The Pineapples
White Stripes

Five question marks:
'Til Tuesday
Blondie
Dino
Bush
Twisted Sister

At least a few unidentified things:
The mannequin in the shop windowp
The two guitar-toting guys walking in the middle
The group of people in white who are rejoicing (or something)
Two squash on the fruitstand
The big fern in the lower left corner
Two young boys on left (in full pic)
Whatever's in the pet shop window (in full pic)
The little dog in the lower left corner (in full pic)