Here's one that is probably unknown to most. It's a Marlin 50. Manufactured from 1932 to 1934 with a total production of only a couple thousand. Magazine fed, open-bolt, semi-automatic and I've read the first semi offered to the civilian market. Has a tendency to go rock and roll with a little wear on the sear which probably contributed to it's demise.
When I got this one it was rusty, had a broken stock (in two pieces) and was missing a couple of parts. She still fires fine and has a nice shot group.