UndergroundCellar.com offers an extensive selection curated, limited wines—with a twist. Wines are handpicked by a team of sommeliers, who scout out rare varieties and release a limited supply as an exclusive deal within a brief time window. Each sale comes from a superb winery, and customers can browse both winemaker and tasting notes before deciding on a purchase.

That's where the twist comes in. A percentage of purchased bottles receive free "upgrades," which replace them with more coveted or special wines. The upgrades can entail a rarer vintage, an autographed bottle, or a larger format, among other surprises. Buyers discover their upgrades after checkout, at which they can then decide whether they want their wines shipped immediately or stored in the CloudCellar to save on multi-bottle shipping at a later date.