Cool page! I go to the Monterey Historics a lot and have seen a lot of the old GP cars and drivers. Last year they had a bunch of Auto Union cars including a V-16 with Hans Stuck driving.
Also there have been guys like Phil Hill, Stirling Moss, Juan Manuel Fangio, Jack Brabham, Denny Hulme, Chris Amon, Parnelli Jones, Dan Gurney, Caroll Shelby, etc. usually driving the cars they drove way back when.
My favorites are the old Benz cars like the W196. One year Fangio was driving this car for a 5 lap demo. He drove slowly the first lap, with a 600SL in front of him taking pictures. He gradually increased the pace, forcing the 600SL to drive faster. Finally on the third lap the 600SL spun, and Fangio goosed the W196 and did two hot laps before returning to the pits. Needless to say, the crowd went nuts.