The '
Intro To Jazz' Thread has a lot of solid suggestions... Really depends what you are looking for... classic/traditional jazz, big band, bebop/fast beat, avant garde, fusion...
Duke Ellington, Davis (In a Silent Way/'Round About Midnight), Coltrane (A Love Supreme), Thelonious Monk (Brilliant Corners), Charles Mingus (Ah Um/Black Saint and The Sinner Lady) are solid starting places...