I keep little flute glasses in the freezer on the door, near the bottle. Grab glass, bottle, pour, put the bottle back for next time.
In fact, now I think of it, the bottle of limoncello I bought CAME with the glasses. And they really are perfect. Of course, have to fill them several times. But they're the right size that the liqueur is still cold by the time I get to the bottom of the glass (and need more).