Short notice, but Johnny Carson fans will probably want to check out PBS' latest entry in the American Masters series that premiered last night. At least on my local PBS affiliate, there are encore presentations scheduled for tonight at 8PM central and on Friday at 1AM central. Check your local PBS schedules.
I only caught a few minutes last night, but what I saw looked interesting and I'm planning to watch tonight's rebroadcast.
Johnny Carson: King of Late Night 