Wait, popular? or "important"? As in "influential to many many others"...

the latter might include
My Bloody Valentine - "Loveless"
or
Primal Scream - "Screamadelica"
but probably wouldn't be classified as popular.

just curious before we start...

Aphex Twin - "Selected Ambient Works Vol. II"
Joy Division - "Closer"
My Bloody Valentine - "Loveless"
Pavement - "Slanted & Enchanted"
Pixies - "Surfer Rosa"
Radiohead - "OK Computer"
The Smiths - "The Queen Is Dead"
Sonic Youth - "Daydream Nation"
The Velvet Underground & Nico - s/t
The Velvet Underground - (third LP)

off the top of my head

miles davis - kind of blue
sex pistols - never mind
beatles - sgt peepers
led zep - zoso
throbbing gristle - heathen earth
can - ege bamyasi
nirvana - neverthemind
clash - london calling
who - who's next
stevie wonder - talking book, or some other one

Funkadelic - "Funkadelic"
The Pretty Things - "SF Sorrow"
The Beach Boys -"Pet Sounds"
Black Sabbath "Paranoid"
Pink Floyd "The Piper at the Gates of Dawn"
Big Brother and the Holding Company "Cheap Thrills"
Nico "The Marble Index"
Stereolab "Emperor Tomato Ketchup"
Beastie Boys "Paul's Boutique"
Gary Numan + Tubeway Army "Replicas"

top ten most influential artists for pop culture at large:

1. billy ray cyrus
2. john tesh
3. milli vanilli
4. NKOTB
5. Paula Abdul
6. Dave Koz
7. R Kelly (not as a musician, but as a pederast)
8. Michael Bolton
9. Vanilla Ice
10. David Hasslehoff

This is always a difficult task because 1) no matter how matter how hard you try this list is still subjective and 2) it's difficult to put a limit (top 10) on something subjective. It's still fun to do.
The list in no particular order:

Radiohead - OK Computer
The Beatles - Rubber Soul
Luscious Jackson - Natural Ingredients
The Who - Who's Next
Interpol - Turn On The Bright Lights
The Rolling Stones - Let It Bleed
Pixies - Doolittle
Roxy Music - Siren
The Beatles - The Beatles (the white album)
Van Morrison - Astral Weeks

*Bob Dylan - "Highway 61 Revisited" (Dropped right in the middle of the 60's, it sounds fresher than a lot of the stuff it influenced. And hell, track one is "Like A Rolling Stone," that's reason enough for inclusion.)
*Public Enemy - "It Takes A Nation Of Millions To Hold Us Back" (Sounds as vibrant today as it did back then, thanks to Hank Shocklee's production that sounded something like controlled chaos. This one dropped before gangster rap came along and dumbed down the genre.)
*The Beatles - "Sgt. Pepper's Lonely Hearts Club Band" (Has any musical reinvention ever sounded better or more refreshing? It stands out in an era when a lot of great music was being made.)
*Beastie Boys - "Licensed To Ill (I feel odd including this one because, well, it's not their best work, and let's be honest, few people have gotten further on a combo of style and marginal musical talent than the Beasties. This one made rap, or should I say, the Beasties' version of it, accessible to the white masses, which helped kickstart the genre to wider appeal.)
*Al Green - "I'm Still In Love With You" (It has legs because it bridges the gap between Motown and the vibrant 70's R&B sound that reminds us how crappy that genre has become in the Age of Hip Hop. The title track is fantastic, and Green's cover of Kris Kristofferson's "For The Good Times" is just as good.)
*AC/DC - "Back In Black" (So much heavy metal from the early 80's through the death of hair bandedness is damn near unlistenable these days, it really dates itself. But for whatever reason, this album still has legs, maybe because it's just an album about sex and booze, and who doesn't like those?)
*Pearl Jam - "Ten" (I pick this instead of Nirvana's "Nevermind" because "Ten" is slightly more accessible. In terms of straight popularity, Pearl Jam never got to this level with any subsequent release, and you'll still hear "Black" and "Jeremy" on a lot of rock stations.)
*Miles Davis - "Kind Of Blue" (If you like jazz, then you like this, simple as that. People will say it can sound repetitive in spots, but hey, to each their own.)
*The Cure - "Kiss Me, Kiss Me, Kiss Me" (A true test for this thread would be this: Would you buy this album today if it was brand new and you'd never been exposed to it? This album passes that test. It's bouncier than most of their catalog, but hell, how can you not like "Just Like Heaven?")
*New York Dolls - "New York Dolls" (If you could take a time warp back to the early 70's, you'd find that this album didn't sound like anything else, but in the years afterward, a lot of acts would use it for a blueprint.)

1. Jamiroquai ... "Funk Odyssey"
2. Simple Things ... "Zero 7"
3. Jill Scott ... "Jill Scott"
4. Sade ... "Love Deluxe"
5. The Murmurs ... "Murmurs"
6. Smashing Pumpkin .. "Mellon Collie & The infinite sadness"
7. REM ... "REM In Time: The best of REM"
8. STING ... "The very best of STING and The Police"
9. LennY Kravitz ... "Greatest Hits"
10. SimplY Red ... "VerY Best of SimplY Red"