FDR did, a switch in time saved 9.
FDR threatened to add 3 liberal Justices to the court to make it 12.
One of the better pieces on this on the net (See: http://www.fff.org/blog/jghblog2009-01-15.asp) starts out
Among the things that pro-New Deal advocates hardly ever bring up is one of the most shameful acts by a president in U.S. history. Thats the infamous court-packing scheme that President Franklin Roosevelt proposed when the Supreme Court was declaring much of his New Deal unconstitutional.
It would appear that the Democrats, like Obama, have not only failed to bring it up, they don't even know it happened! (IGNANT dude said "unprecedented" proving he had no clue).