What is your favorite album cover?

T. Rex - Electric Warrior (rock personified)
Miles Davis - Bitches Brew (also see Santana Abraxas & Miles Live)
Any Roger Dean cover (Yes, Osibisa, Uriah Heap, Asia, etc.)
It's a Beautiful Day
Zappa - Hot Rats
Bowie - Ziggy Stardust
Jane's Addiction - Nothing's Shocking
Guns 'n Roses - Appetite for Destruction (Robert Williams original)
The Dead - Axomoxoa (Rick Griffin is the BEST & his lettering is on many albums)
.....so many more......

I know it's schmaltzy but 'Woodstock=Music From the Original Soundtrack and More'. I was a kid but loved the neighborhood hippies and that album photo identifies that period of my life. Too bad that era's culture changed so radically during the 1970's.

Brain Salad Surgery & Ambrosia's Road Island. It's a Ralph Steadman drawing.  
Court of the Crimson King is music room wall art. One of the best.

Dark Side of the Moon

Jethro Tull - Stand Up is a good one, also Roxy Music - For Your Pleasure as well as the first eponymous release. I also like the cover of Blue Skies by Stan Getz.