All Music Guide lists a genre called "obscuro": "he weird, the puzzling, the ill-conceived, the unclassifiable, the musical territory you never dreamed existed." Here are all the albums they give 4.5 stars (no 5 star albums, perhaps understandably):
"We All Together," We All Together
"Tonto Rides Again," T.O.N.T.O.'s Expanding Head Band
"The Music of Raymond Scott: Reckless Nights and Turkish Twilights"
"The Many Sides of Lee Lee Hazlewood"
"The Essential Marcos Valle, Vol. 2"
"The Electric Lucifer," Bruce Haack
"The Cycle Breed," Davie Allan
"The Complete ESP-Disk Recordings," Pearls Before Swine
"The Best of Lieutenant Pigeon"
"The Best of Bardot," Brigitte Bardot
"The Amazing New Electronic Pop Sound of Jean Jacques Perrey"
"Songs of Experience," David Axelrod
"Song of Innocence," David Axelrod
"Seriously Deep," David Axelrod
"Samba '68," Marcos Valle
"Psych-Out [Original Motion Picture Soundtrack]"
"Powerhouse, Vol. 1," Raymond Scott Project
"Polnareff's," Michel Polnareff
"Philosophy of the World," The Shaggs
"Permanent Damage," The G.T.O.'s
"Os Mutantes," Os Mutantes
"One Nation Underground," Pearls Before Swine
"Music for Scattered Brains," AZ
"Meet the R. Stevie Moore!," R. Stevie Moore
"Manhattan Research, Inc.," Raymond Scott
"Ludo," Ivor Cutler
"Love and Other Crimes," Lee Hazlewood
"Life in a Scotch Sitting Room, Vol. 2," Ivor Cutler
"Legend of a Mind: The Underground Anthology," Various Artists
"Jewels Were the Stars," Pearls Before Swine
"Hush Little Robot," Bruce Haack
"Everything Is Possible: The Best of Os Mutantes"
"Dance to the Music," Bruce Haack
"Contact," Silver Apples
"Constructive Melancholy: 30 Years of Pearls Before Swine," Pearls Before Swine
"Bubble Pop: 20 UK Pop Oddities," Various Artists
"Balaklava," Pearls Before Swine
"74-76," Destroy All Monsters
"2," We All Together
"1968 to 1970: An Axelrod Anthology," David Axelrod
Of the one's I'm familiar with, I wouldn't think Raymond Scott was too weird or bizarre, though he did do some experimental stuff:
Bruce Haack is super-weird. I don't really like his stuff at all.
David Axelrod is a great, creative jazz/funk composer. I don't think of him as weird; maybe I just haven't heard the right cuts.
Some of the other names were mentioned already.