It allows you to keep your 2d6 groove when rolling d6+3.
As an alternate die for "best of" die roll rules (gives a minimum, but reduces odds of higher rolls).
… or "worst of" rolls, "discard lowest", "pair matching" rolls (a la Risk).
Pictogram generator. The three spots are in a straight line, so roll five and you get a pattern of short lines.
Random triangle shape deployment generator. (as above)
Wind direction generator (again, using the straight line concept)
It would be great of Oh God, Anything But A Six!.
Useful in QILS, also.
Forest generator … look at all the t'rees!
Elevation marker when you are not using elevation rules.
Anniversary reminder die. Make sure you get married on March third.