A new type of tileable pentagon has been found!
There are many kinds of tiling that use just one shape of pentagonal tile (and its mirror image if necessary). Up to now, these tiles fell into 14 types (see http://www.mathpuzzle.com/tilepent.html ). Now another has been found.
I did a lot of research on this five years ago, and found many tilings that seemed to be new, but no new tile shapes. My computer search hadn't gone far enough to find this new type. I'm a little miffed that I didn't get there, but very happy to see there was still (at least) one to be found. Who knows, there may be even more out there.