Here is a quote from the weblog that triggered this question ( http://www.sfbg.com/blogs/music/2007/10/spooked_sounds_2_more_lost_alb.html - http://www.sfbg.com/blogs/music/2007/10/spooked_sounds_2_more_lost_alb.html ):

Pink Floyd - The "Household Objects" recordings, London, c. 1973

Whatever the contemporary consensus of Pink Floyd by current garage-indie-minimal-electro-punk hipsters, very few of these snobbish prog haters know of Waters and Co.’s DIY recordings in the fall 1973, otherwise known as the "household objects" experiment. It seems the band was attempting the ultimate punk statement years before Johnny Rotten famously sported an "I HATE PINK FLOYD" T-shirt in the Sex Pistols. Conceived by Waters in the wake of forays into the post-Syd Barrett ambience of Atom Heart Mother, Obscured by Clouds, and Meddle, "Household Objects" had the band using random, detuned objects d’trouve like wineglasses, rubber bands, and pots and pans to create what would have been a most bizarre follow-up to Darkside of the Moon. However sessions ground to a halt within a few months after the monolithic “Shine on You Crazy Diamond” began to take shape and the maximalist jazz-rock opus Wish You Were Here soon followed.

 

I guess one of the better known ones was the Jethro Tull recordings in France for the follow up to "Thick as a brick". These were abandoned at the time, but have subsequently become available on the "Nightcap" album.

 

It seems to me that had those recordings been seen through to fruition, and been released instead of "Passion play", Jethro Tull might have followed a completly different course.

 

"Sisyphus has attained legendary status among rock critics, Chicago fans, those who’ve heard parts of it and those who have only read about it." —from liner notes by Bill DeYoung

Formed in its namesake city in 1967, Chicago is the first American band ever to propel albums into Billboard®’s pop Top 40 for five consecutive decades, and is among the most successfully charting U.S.-grown acts of all time. Now, another page in the band’s history is revealed with the long-awaited release of Stone Of Sisyphus, the once shelved album that has attained legendary status among fans and critics alike. Recorded in 1993 and originally intended as Chicago XXII, the disc marked a return to the genre-transcending, adventurous fusion of sounds that defined the group’s 1970s-era heyday. Three tracks from it surfaced on Rhino’s 2003 Chicago box, but the album itself is previously unissued—now, this momentous release also features four incredibly rare bonus tracks.

That's true, but it wasn't intended as the album "Ship of memories". It merely contains tracks from this session, a rerecorded Hocus Pocus and for instance "Red sky at night", which was originally titled "Avondrood" and it appeared, with dutch lyrics, on a compilation album (with collaborations between dutch poets/writers and rock/pop bands). Altough there are some nice tracks on this album, I don't consider it essential however. And the cover ... you're absoluteley right (but this is all off topic of course).

 

http://youtube.com/watch?v=HdYtihy5ljk - http://youtube.com/watch?v=HdYtihy5ljk

 

Video of it! I'm not sure how many have seen this.

 

XYZ was the proposed name for an abortive supergroup. The name XYZ is taken from eX-Yes-&-Zeppelin as the group consisted of ex-Led Zeppelin guitarist Jimmy Page, along with ex-Yes members Chris Squire (bass guitar, vocals, keyboards) and Alan White (drums). Page believed the band needed a strong vocalist and sought out former Led Zeppelin frontman Robert Plant — Plant did attend one XYZ rehearsal in 1981 but decided not to join the group, citing his dislike for complex progressive rock. Without a commitment from Robert Plant, the project was shelved shortly thereafter. Squire has also mentioned Page’s personal problems at the time were one of the motives for the dissolution of the band. Since the mid 1990s, a number of bootleg tracks have surfaced, originally recorded by XYZ at Chris Squire’s home studio at New Pipers, in Virginia Water, Surrey, during April 1981. They are believed to have been sourced from demo tapes stolen from Jimmy Page’s house at Cookham, Berkshire, in 1987. These consist of four pieces: two instrumentals (the riff from one of which was used on The Firm’s “Fortune Hunter”; the other was later incorporated into the 1997 Yes song “Mind Drive”), plus vocal numbers known as “Telephone Secrets” aka “Telephone Spies” (previously attempted by Yes as “Song No. 4 (Satellite)” during the sessions for Drama) and “And (Do) You Believe It” (or “Can You See”). The latter track was recorded by Yes in 2001 and released as “Can You Imagine” on Magnification. It is quite possible other songs were also attempted but nothing else has been released publicly. With XYZ’s future now in limbo, Squire and White recorded a single called “Run With the Fox”, in October 1981 at New Pipers, before forming Cinema, with guitarist Trevor Rabin and keyboardist Tony Kaye. Rabin attempted to rework the XYZ material along with his solo songs for the new group, but abandoned the project with the reformation of Yes with the addition of singer Jon Anderson, and the recording of the album 90125 in 1983. In 1984, Jimmy Page joined Yes on stage, playing “I’m Down” during a concert in their 9012Live tour at Westfalenhalle in Dortmund, Germany