One more Allied gambit comes to mind. No idea who had the original idea, but I’m calling it…
The Berlin Bank Job
Moves: US takes Denmark. UK transits Danish Straits to capture Germany.
Plan: The Allies take advantage of a German player who leaves Denmark and Germany lightly (or un-) defended. In a one-two punch, the US captures Denmark, opening the door for the UK to sail into the Baltic and amphibious assault into Germany, capturing Berlin and stealing Germany’s money. Executed at the right time, this move can almost single-handedly save Moscow by preventing Germany from purchasing new units for at least one turn. Also, the UK gets a huge one-time income boost.
Problems: In order to keep the German player from becoming alarmed and reinforcing Denmark and Germany, the Allies can’t have a huge troop buildup in advance of the operation. This means that minimal force must be used, which means that those units committed to Denmark and Germany are essentially on a suicide mission. This includes any British naval units which enter the Baltic, as they’ll be trapped there until Denmark is again liberated or they’re killed by the Luftwaffe, whichever comes first.