My old buddy Roger Freedman was the first of (so far) twenty people to remind me that Superman was on a U.S. postage stamp once before — in 1998 as part of the "Celebrate the Century" promotion.
Above, the stamp on the left is the 1995 Canadian stamp I just mentioned. I believe the image is a composite of two drawings, both by Joe Shuster. I haven't made a side-by-side comparison but the train seems to be off the cover of Superman #3 and the Superman drawing is from an interior panel in one of the early issues. (Anyone want to identify which one for me so I don't have to dig around?)
At right above is the 1998 U.S. stamp which uses a drawing from the cover of Superman #2. It was most certainly pencilled by Joe Shuster and was inked either by him or by Paul Cassidy, who was his assistant for a brief time.