For me, nothing overly serious. One or two cracked ribs, knee hyperextension, and the worst bruise I ever saw from doing a low kick and my partner blocking with his knee. I was limping for about three days. Bleeding nose and minor bruises countless times.
And this is during the course of eight years. I can only imagine the things to come through getting more serious about full-contact training
edit: forgot getting kicked in the groin a few times and concussions from being thrown at ridiculous angles