The one I'm up and dancing to right now is Waka Waka (This Time for Africa) by Shakira! I think this one is at Piazza Duomo in Italy? [youtube.com...]
Spent the afternoon watching Flash Mob videos from all over the world, malls, community common areas, many different places, different styles of music, orchestras and dance. But it wasn't all joy. Some of it had tears rolling wondering why we can't have this much joy in our everyday lives.