Wrapping Squares
mathani had a great image on their tumblr today, folding up a 2x5 rectangle to exactly cover a square of area five.
Post: http://mathani.tumblr.com/post/128971343009/a-5-by-5-square-polygon-is-being-fully-covered
I made this to understand the construction a bit more, and it really is nice, with a strong origami flavor.