Not commuting, but a few years ago my bf and I and another friend were doing a summer night ride on rural roads. We had good headlights, there was no traffic, etc. A huge raccoon jumped out of the ditch right into the rear wheel of my bf's bike. Took the bike right out from underneath him. He went down, was knocked out (had helmet). Trip to ER, Grade 3 concussion, minor brain hemorrhage, bruises but nothing else broken.