Limoncello is a sweet, lemon-flavored liqueur that originates from the southern regions of Italy. It's usually served chilled and straight up, as a lovely after dinner digestif. It has a strong lemon flavor, but contains none of the sourness associated with lemons, since its made by infusing the peel of the lemon, rather than the juice.
And SiNCE its merely lemon peel infused into high proof alcohol, it means you can make it at home! In bulk! It only takes three ingredients - lemon peels, sugar, and grain alcohol, and about three months.