From Science Friday, perhaps the most purely enjoyable science story of the year to date, about the Dance of the Peacock Spider.
Seems we've been seeing many examples of species showing traits we think of as human lately. Using tools, like crows, or mourning the dead, like elephants, or having local dialects in languages, like songbirds. But this is the best example of a species shaking it on the dance floor I've ever seen.
Tho' arachnid sex doesn't always have a happy ending -- at least for the male.