A philosophical instrument used for divination in Philip Pullman's book The Golden Compass and its sequels. I might call it a "psionic device," but that doesn't seem steampunkish enough.
Actually, this is an Uno game with circular cards, packaged to resemble an alethiometer.
This did not keep it from startling me. Even though I knew the movie was on the verge of release.
(For a nice pocketwatch casemod, see this.)