Here's a cool ScienceDaily report on how dancing ability and vocal mimicry may share a mechanism. The data are on species, not individuals, but I think it holds at the individual level too. Girls tell me I'm a great dancer, and I can imitate voices pretty easily and develop a decently native accent in a foreign language without too much trouble. I can't think of counter-examples off the top of my head, just more confirming points, like this adorable 10 year-old girl at the tutoring center I worked at. She had an amazing knack for accents and kept a pretty good beat while dancing. One of those natural actress types (and of course that's what she wanted to be when she grows up).
You see this among human "species" or racial groups too. Blacks are great at vocal mimicry -- beat-boxing and Michael Winslow-esque sound effects, in addition to dancing skills. East Asians can never find the beat (which is why they stick to easy marching music like techno), and they don't dominate in beat-boxing or doing impressions as stand-up comedians, etc. Ashkenazi Jews are great at vocal mimicry, but I'm not sure about dancing skill. The stereotype is that they're goofy and klutzy, but that may be just their self-deprecating humor and neuroses showing. Anyone looked at how over or under-represented they are among professional dancers? Again, hard to think of counter-examples here.
This relates to what I said about group differences in cognitive profile and musical styles. (Goddamn, was that really three years ago?) If you're good at verbal things, you'll be good with melody and rhythm, while if you're good at visual-spatial things, you'll be good with harmony. These tend to go together, so most skilled musicians are good at both. But there are interesting dissociations too.