Many outlets have a bridge clip on each side of the receptacle. (I have seen these used for things like making one outlet switched on one side but always-on for the other.)
Question: If you have a handle-tied 2-pole breaker, can you cut the hot clip and run one phase to each half of the receptacle? Each outlet would be 120 volts, but the voltage between the hot on each outlet would be 240 volts.
I have heard of people doing this, and it works fine, but does it meet code?