Do you know what prototype portal does? Like I've got 9 of them or so at the moment (if I remember right) and I have to really fight the urge to include them in any deck containing artifacts.
Voltaic Key is about the only other card I know of recently with that kind of utility. Of course going a little further back you have the Jitte or Skullclamp. All objectively good cards because they make just about literally any deck you could build better just by being there.