A Boy and His Dog by Harlan Ellison
A Gun For Dinosaur by L Sprague de Camp
The Cave of Night by James Gunn
A Pail of Air by Fritz Leiber
Lulungameena by Gordon R. Dickson
Since we're discussing classic sf, I'm going to prosthletize for X-1 and Dimension X. Two radio shows from the 50's which dramatised a whole whack of golden age science fiction by the likes of: Ray Bradbury, Robert Bloch, Robert Heinlein, Issac Asimov, Kurt Vonnegut, Clifford D. Simak, H. Beam Piper, Robert Sheckley, Fredrik Pohl, L Sprague de Camp, Fritz Leiber, etc, etc. Awesome for listening to on trips!
Available (free - public domain is good!) from Old Time Radio groups like the OTRR Distro Group:
http://groups.yahoo.com/group/OTRRDistroGroup/
Episode lists for X-1 and Dimension X:
http://otrsite.com/logs/logx1001.htm
http://otrsite.com/logs/logd1013.htm