What should I check out?

Morton Feldman "Coptic Light" (Michael Tilson Thomas cond.)
John Coltrane "Live at the Half Note" (Impulse)
Cecil Taylor "Unit Structures" (Blue Note)
Orlando Gibbons "Fantasias" (Jordi Savall-Astree)

Johnny Cash's series of American recordings

Wow, some great responses . . .

I'll second Tvad's Gateway recommendation, and add the eponymous first album, (from 1974-ish) to the mix.

Josquin des Pres - "missa L'homme arme sexti toni" - performed by the Tallis Scholars.

Bebo & Cigala (Bebo Valdez & Diego "El Cigala") - "Lagrimas Negras"

All of John Holloway's recent baroque-violin recordings on ECM, with works of Biber, Schmeltzer, Veracini, & Bach.

Eric Dolphy & Booker Little - "Far Cry"

Gidon Kremer & Kremeratica Baltica - "Silenco"

Charles Dodge, "Any resemblence is purely coincidental."

sweet; keep 'em coming...I will definitely check many of these babies out.