Albert Marcoeur

French avant-garde acoustic jazz, filled with moments of absurdity and cacophony. From his self-titled LP from 1974.
"Tu Tapes Trop Fort":

"Simone":

Mikio Masuda

Japanese keyboardist Mikio Masuda with a legitimately smooth track, and quite possibly the best/worst album art I've seen in a while.
"Moon Stone" from the 1977 album of the same name:

William De Vaughn

diamond in the back, sun roof top, diggin' the scene with a gangster lean.
1974 single, "Be Thankful for What You've Got":

Weather Report

for all you jazz-funk enthusiasts out there, Weather Report with "Teen Town" featuring the amazing Jaco Pastorius on bass!

Lonnie Liston Smith

"Colors of the Rainbow" from Watercolors (1991):

Sun Ra

anyone who has an affinity to the absurd, psychedelic, or metaphysical and hasn't yet heard of Sun Ra ought to do some immediate research. This is from 1956:

Piero Piccioni

both from the film soundtrack to the Italian thriller Colpo Rovente:
"Red Hot" (1969)

"Colpo Rovente" (1969)

Stark Reality

"Acting, Thinking, Feeling (Part1)", live 1968:

Johnny Hammond

John Robert "Hammond" Smith, playing some classic jazz-funk from late in his career, "back to the projects" from Gambler's Life (1974).

Marvin Gaye

marvin gaye performing live, "what's going on/what's happening brother" from the 1971 album What's Going On:

Frank Zappa & The Mothers of Invention

zappa and the mothers, live studio session for the BBC, 1968. ignore the repetition of the opening bit...:

Alice Coltrane

filmed for BBC, 1992