Dead Kennedys-
Bedtime For Democracy
Blanks 77-C.B.H.. It’s best on the 10"gatefold Lp version.
I second Flippers live album!
Natty Dread -** Bob Marley**
The story behind the cover of Who’s Next is that the band was travelling through Welsh coal country and were inspired by both (1) the pylons set to anchor the man-made hills of mining waste and (2) an ample supply of the brewer’s art. Siezing upon the visual reference to “2001 Space Odyssey” and the obvious irreverent possibility resulted in:
Southern Rock meets Frank Frazetta - Molly Hatchet
I also have very fond memories of the Ohio Players cover art.
Commander Cody - Ozone
How can I forget…
Still have that on vinyl, too. Great cover and great album.
Does anyone remember the original album cover for L.A.Woman by the Doors? It had kind of a yellow plastic see-through thing going on but then they went to something cheaper. The Doors always had kind of neat album covers.
Sunset Ride by the old Colorado band Zephyr was a beautiful example of vintage travel poster art decades before this became trendy.
Great Og. I really must be careful posting and mixing martinis.
Yup, I owned it back then. All my albums burned in a fire in 1977, and my collection’s never been the same.
My votes:
Another vote for In The Court of the Crimson King. I had to stop wearing this as a t-shirt, though, because it gave both of my kids nightmares when thy were little.
Brain Salad Surgery by Emerson, Lake and Palmer
Another vote for Thick as a Brick, in its original issue, and for Wish You Were Here.
Plus one I’m surprised hasn’t appeared yet: Big Bambu by Cheech y Chong, which was a giant Big Bambu rolling paper package and even had a paper in it big enough to smoke a gym sock (with apologies to FZ fans for the gym sock reference…). 
“Undertow” by Tool - that red multi-tentacled thingy creeps me out.
“The Hurting” by Tears for Fears - the one with the little boy crying.
“Seal” (1994) - he looks strikingly alien in that pose.
How about this Dylan poster that was included inside one of his albums: (Greatest Hits Vol. 1?)
http://www.artlex.com/ArtLex/Images/artwork/poster.glaser.dylan.gif
And this Lennon poster that was included inside the Imagine album:
Good answers so far; and too many to mention. Pink Floyd had a slew.
I nominate “Ghost in the Machine” by the Police, simple yet effective work of art. The idea behind it makes it all the more adorable.