International Currency Bills
I've always wondered who designs the world's currency? The intricate fine engraving required to build a hard-to-counterfeit bill is a special art unto itself. Cigar box labels are full of beautiful detailing, too. I think this type of handiwork is something to learn from when designing anything for the luxury market. The beautiful flourishes and detailing might just inspire your next liqueur or wine label.
(thanks to Armin at SpeakUp)