I don't have a typically wood working work bench. I have a couple of work benches I made from some salvaged counter tops on a frame made of 2x4's and 2x2's. While they work great for being a nice flat surface for stacking things on, they lack the work holding capabilities of a real work bench. It also isn't sturdy enough to not want to move around while using a hand plane.
Recently I added a hold down clamp to my bench, it was something I had gotten at a yard sale my grandma was having. Grandpa had never installed the clamp, it was new in the box.