I want one of these in "plug" form factor that uses a normally-closed relay rather than normally-open. The reason being that the internal power supply and microcontroller could fail by shutting down, preventing things from working at all. There's nothing that can be done about the microcontroller failing while holding the circuit open, though, but power supply failure has been a reoccurring but infrequent thing for me lately and it would be nice to cover that case well.

Edit: For small do-it-yourself computer clusters you probably want it to fail normally-open, this would be for non-redundant stuff