SLeeper lps of 70s....

everything released by "Big Star" - Alex Chilton's band. Winner. Hands-down.

"...Before it broke up, Big Star created a "seminal body of work that never stopped inspiring succeeding generations" in the words of Rolling Stone,[1] earning recognition decades later, according to Allmusic, as the "quintessential American power pop band" and "one of the most mythic and influential cult acts in all of rock & roll"..."

If you want a real sleeper,check out
Chilliwack "All Over You"

The Book of Invasions, A Celtic Symphony
Horslips

Blue Jays
Justin Hayward/John Lodge

Butts Band
The Butts Band

The Northstar Grassman And The Ravens
Sandy Denny

City Boy
City Boy

Quah
Jorma Kaukonen

Sleeper Catcher
Little River Band

Hero and Heroine
Strawbs

Second Chapter
Danny Kirwan

Wishbone Ash's first album

Here's a few:

April Wine-Harder, Faster
Charlie-Lines
Trooper-Knock'em Dead Kid
Billy Thorpe-Children of the Sun
Prism-Prism & See Forever Eyes
Amazing Rhythm Aces-Too Stuffed to Jump

Are you looking for unappreciated works of popular artists, or underappreciated artists?

The following are artist and specific recordings that deserved a lot more attention:

Graham Parker: "Squeezing Out Sparks"

Michael Hurley and the Unholy Modal Rounders/Jeffrey Fredericks and the Clamtones: "Have Moicy"

Kate and Anna McGarrigle: Self Titled

Martha and the Muffins: "Metro Music"

Tonio K: "Life in the Foodchain"

Musicslug
I was at two Art Ensemble of Chicago Concerts - one in Warsaw in late 70s and one in Chicago in late 80s. Concert in Warsaw (big auditorium) was beyond believe. They started an hour late because of electrical/equipment problems but played to 1:30AM (almost 4 hours) to compensate for that. People didn't want to let them leave. Since Lester Bowie death in 1999 I lost a little bit of interest. Without his cutting trumpet it just not the same. Not too many people in Chicago, where I live, know about Art Ensemble of Chicago - what a shame.

Musicslug, Great call on on Art Ensemble of Chicago! Here are a few 70's goodies I enjoy:

Count Basie "The Gifted Ones", Pablo 2310 833
Count Basie "For the First Time", Pablo 2310 712
Ray Brown "Brown's Bag", Concord CJ-19
Ray Bryant "All Blues", Pablo 2310 820
Ray Bryant "Montreux '77", Pablo 2308 201
The Cars "The Cars" Elektra
Benny Carter & Dizzy Gillespie "Carter, Gillespie Inc" Pablo
The Clash "London Calling", Epic
Elvis Costello "Armed Forces", Colubmia
Duke Ellington "This One's For Blanton", Pablo 2310-721
Duke Ellington "Duke's Big 4", Pablo 2310-703
Fleetwood Mac "Rumors"
Funkadelic "One Nation Under A Groove", Warner Bros
Great Jazz Trio "Direct From LA", East Wind EW10005
Great Jazz Trio "Love For Sale", East Wind
Buck Hill "This Is Buck Hill", Steeplechase SCS-1095
The Jackson "Destiny", Epic 35552
Michael Jackson "Off The Wall", Epic
Hank Jones "Live In Japan", Trio PAP-9177
Ricki Lee Jones "Ricki Lee Jones", Warner Bros
Art Pepper "Straight Life", Galaxy GXY 5127
Oscar Peterson "Jousts", Pablo 2310 817
The Police "Regatta De Blanc", A&M SP-4792
Todd Rundgren "Something, Anything", Bearsville
Steely Dan "Pretzel Logic" ABC Records
Supertramp "Crime of The Century" A&M
10cc "Deceptive Bends", Phonogram

it's not rock, but 'native dancer' by wayne shorter and milton nascimento has always seemed to me like a very overlooked LP. pretty easy to find in good condition, well engineered, and absolutely beautiful music - it's 'fusion', in the sense that it blends genres (Brazilian and jazz), but it's really just about two huge talents working beautifully together.

also: I'm not sure they qualify as 'sleepers' anymore, but Nick Drake's 3 LPs, especially 'Pink Moon' were beneath the radar for years. way ahead of his time, gorgeous and timeless music.

and: they were 'big in Europe' and under-appreciated at home, but the Art Ensemble of Chicago was doing their best work during that period. 'les stances a sophie', 'people in sorrow', 'jackson in your house', 'tutankhamen', 'phase one', 'fanfare for the warriors' are all amazing albums - once again: huge talents working in perfect synergy...