There are SO MANY but here are the first three that came to mind:
Alton Scales' 'White Man's Leavings' monologue from "The Sign in Sidney Bruistein's Window"
Tom's often done 'Opium dens' monologue from "The Glass Menagerie"
Hissom's long monologue from Yasmina Reza's "Art"
"Smart! And into all those exotic mystiques -- The Kama Sutra and Chinese techniques. I hear she knows more than seventy-five. Call me tomorrow if you're still alive!"