In my area (northern California), if you spend a lot of time social ballroom dancing, you'll use most of the "official" American-style competition dances. But you'll also learn some extra dances that aren't part of the normal ballroom lineup. For example, Lindy Hop, hustle, West Coast swing, salsa, nightclub two-step, and Argentine tango are all pretty popular around here and you'll find people doing all of them at many of the local ballroom dance venues.
My impression is that several of the dances I just listed aren't widely taught outside North America. (Yeah, yeah, obviously Argentine tango is big in Argentina!) Which got me to wondering, what are people doing alongside the ballroom dances in other parts of the world? There must be some neat dances out there that few of us around here have even heard of.
Anyone want to name and describe some other popular regional social dances that appeal to the ballroom crowd?