Irwin Quick-Grip Clamps, Irwin Tools, varying prices
I used to only use iron C-clamps for my woodworking because they were what I had on hand. But it was always a pain to screw them to the right width and then use scrap wood in between the clamp and piece I was working on so as not to mar the wood. Quick-Grip clamps changed all that. They adjust to the right size in a snap, and then tighten with a few quick squeezes on the trigger. With the attached rubber feet you no longer have to worry about leaving marks in your work, and they come in a dizzying array of sizes.