Here are some articles on square dancing. If you haven't seen modern western square dance before, here's an unreasonably brief summary: you stand in a square with seven other dancers, and a caller says some words instructing you what to do. You have to figure out where to walk in real time, solving puzzles and making cool shapes along the way. It's really fun, and you should try it!
Square dancing comes in different levels, with the more advanced ones requiring you to learn more things. Most of the stuff here is about challenge dancing, because it's the kind I find the most fun.