Here is an off-the-top-of-my-head list, after having listened to jazz for 30 years. You can't go wrong with these. In fact, these are essential for any musician or educated person. And buy the entire CD, don't just download random tunes:
Kind of Blue - Miles Davis
Nefertiti - Miles Davis
Giant Steps - John Coltrane
Love Supreme - John Coltrane
One Step Beyond - Jackie McLean
Maiden Voyage - Herbie Hancock
Smack Up - Art Pepper
Waltz For Debbie - Bill Evans
Evolution - Grachan Moncur III
Clifford Brown and Max Roach - Clifford Brown and Max Roach (duh)
The Complete Savoy and Dial Studio Recordings - Charlie Parker
Mingus Ah Um - Charles Mingus
That should get you started.